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Since modern cyber-physical power systems are vulnerable to coordinated wide-area cyber attacks, it is necessary to mitigate the potential risk as much as possible. At the planning stage, the defender can utilize software diversity, which is a common phenomenon that the cyber software of different substations comes from different competing vendors. Therefore, different kinds of software may not be exposed to the same zero-day security loophole, preventing the attacker from taking charge of multiple substations at the same time. In this paper, the optimal scheme of software deployment considering long-term risk mitigation is studied. Firstly, the framework of diversity-based cyber defense against malicious attacks is formulated. Secondly, the risk index based on representative attack patterns is constructed, which is the objective to be minimized. Thirdly, considering that the deployment scheme is long-term stable while the operating mode varies with time, we construct a multiobjective nonlinear stochastic programming to mitigate the average risk of operating modes. Then the optimization problem is solved by the multiobjective genetic algorithm. Lastly, results of the IEEE 39-node CPPS and and the Virtual European Grid demonstrate that the proposed method can considerably reduce the attack risk. [ABSTRACT FROM AUTHOR]

This paper presents a new data-driven methodology for power system coherency identification of generator and non-generator buses. This methodology is exclusively based on intrinsic statistical properties extracted directly from observations, without any prior assumption of the probability distribution function (PDF) for the data. The main advances of this proposal are: (i) gathering of statistical information from the data itself despite scenarios where the PDF may change (different inverter-based load and generation scenarios, load levels of the system, and changes in topology); and (ii) assignment of buses into coherent areas without any tuning of parameters, nor manually labeling of huge amounts of training data. This new method, called typicality-based data analysis (TDA), is applied to the correlation metric of the distance between dynamic responses of buses, either voltage angles or frequencies. Simulated signals from a benchmark power system with cases considering the presence of non-synchronous generation and islanding conditions, and real data associated with generation trips in the U.S. Eastern Interconnection are used to corroborate the methodology effectiveness. [ABSTRACT FROM AUTHOR]

With Europe dedicated to limiting climate change and greenhouse gas emissions, large shares of Renewable Energy Sources (RES) are being integrated in the national grids, phasing out conventional generation. The new challenges arising from the energy transition will require a better coordination between neighboring system operators to maintain system security. To this end, this paper studies the benefit of exchanging primary frequency reserves between asynchronous areas using the Supplementary Power Control (SPC) functionality of High-Voltage Direct-Current (HVDC) lines. First, we focus on the derivation of frequency metrics for asynchronous AC systems coupled by HVDC interconnectors. We compare two different control schemes for HVDC converters, which allow for unilateral or bilateral exchanges of reserves between neighboring systems. Second, we formulate frequency constraints and include them in a unit commitment problem to ensure the N-1 security criterion. A data-driven approach is proposed to better represent the frequency nadir constraint by means of cutting hyperplanes. Our results suggest that the exchange of primary reserves through HVDC can reduce up to 10% the cost of reserve procurement while maintaining the system N-1 secure. [ABSTRACT FROM AUTHOR]

The $T$ -Private Information Retrieval ($T$ -PIR) problem is that a user wishes to retrieve a single record from $N$ servers, without revealing the identity of the desired record even if the number of colluding servers up to $T$. Here every server stores all $M$ records and each record can be viewed as a vector over the $q$ -ary finite field $\mathbb {F}_{q}$. To reduce the field size, a capacity-achieving $T$ -PIR scheme based on some MDS array codes for all possible $N>T,M\geq 2$ was constructed by Xu and Zhang in 2019. A key idea in that scheme is to construct some MDS array codes in query phase, whose generator matrices satisfy the recovery property (see (C1) in , page 6), i.e., there exist some specific columns in each generator matrix such that the number of them is equal to the rank of such matrix. We call the set of each column index of those columns in each generator matrix as the column index set. However, that scheme didn’t give an explicit selection of the column index set satisfying the recovery property. In this paper, let $N=d(2t-1)$ , $N>T=dt>1, M\geq 3$ and $d\geq 1$ , under the constraint of $2^{t-1}\geq N$ , we present a novel method to construct capacity-achieving $T$ -PIR schemes over the binary field with an explicit selection of the column index set. Moreover, our scheme has sub-packetization $N(2t-1)^{M-2}$ , which is optimal for all linear capacity-achieving $T$ -PIR schemes determined by Zhang and Xu in 2019. The key to our method is that all locators and column multipliers are precisely selected such that a Generalized Reed-Solomon (GRS) code defined by them has a zero-dimensional subfield sub-code. Compared with all the known capacity-achieving $T$ -PIR schemes for the same non-trivial parameters, ours is the first explicit capacity-achieving $T$ -PIR scheme over the binary field. [ABSTRACT FROM AUTHOR]

In this paper, we propose a symbol encryption method based on the complex-valued symbol multiplication and design the encryption symbol placement for offset quadrature amplitude modulation based filter bank multicarrier (OQAM/FBMC) systems. Specifically, we firstly analyze the encryption and decryption effects of complex-valued symbol multiplication on the original OQAM symbols. Then, by utilizing the intrinsic interference characteristics of prototype filters, a symbol encryption method and the placement design are proposed to simultaneously achieve the encryption of all OQAM symbols and low complexity decryption. Finally, the symbol error rate (SER), average signal transmit power, computational overhead and power spectral density (PSD) are analyzed. Simulation results are consistent with the theoretical analysis and demonstrate that the proposed method outperforms the traditional method based on imaginary-valued encryption symbol insertion in terms of the SERs of both legitimate and illegitimate receivers. [ABSTRACT FROM AUTHOR]

In this paper, we propose two novel modulation concepts based on a simple maximum distance separable (MDS) code and show that these concepts can achieve better error performance than index modulation (IM) and related schemes. In the first concept, we use amplitude and phase levels to form a simple MDS code, whereas, in the second one, in-phase and quadrature components of codeword elements are used to construct the MDS code. We depict practical schemes for using the proposed concepts with orthogonal frequency division multiplexing (OFDM). We analyze the performance in terms of the minimum Euclidean distance and bit error rate. We also show that the proposed techniques exhibit desirable properties such as efficient low-complexity detection, very simple bits-to-symbols, and symbols-to-bits mappings, and a better error performance when compared to the OFDM-IM and related schemes. More importantly, contrary to the vast majority of IM studies that focus on showing the superiority of the IM techniques against conventional modulation techniques, we show that modulation concepts based on a well-known MDS code can achieve better error performance than the IM and related schemes while exhibiting a structure as simple as these schemes. [ABSTRACT FROM AUTHOR]

Multiple-input multiple-output (MIMO) technology with high order signal modulation method has been proposed recently as a scheme to achieve high throughput requirements of next-generation communication applications. However, the use of high-order modulation signals degrades the error rate performance. Generalized frequency division multiplexing (GFDM) has attracted enormous consideration for deploying in new communication scenarios due to its advantages in terms of out-of-band (OOB) emission, spectral efficiency (SE), and latency. Index modulation (IM) methods convey digital information by utilizing transmission entities with adjustable index parameters to provide flexible system design and offer attractive advantages such as energy and SE without increasing the computational complexity. The Multiple-Mode (MM) method permits multiple subcarriers to transmit multiple modes and employs the whole permutation of these modes to convey additional information bits. The proposed MIMO MM-GFDM-IM scheme improves the bit error rate and the spectral efficiency compared to the existing schemes. The proposed method can select the modulation order and the number of modes to achieve the design goals. Furthermore, a system with high modulation order can improve the spectral efficiency when the constellation point is fixed. This paper also proposes a practical and effective MM selection strategy and two low-complexity detectors. [ABSTRACT FROM AUTHOR]

Cloud computing is motivating data owners to outsource their databases to the cloud. However, for privacy concerns, the sensitive data has to be encrypted before outsourcing, which inevitably posts a challenging task for effective data utilization. Existing work either focuses on keyword searches, or suffers from inadequate security guarantees or inefficiency. In this paper, we concentrate on multi-dimensional range queries over dynamic encrypted cloud data. We first propose a tree-based private range query scheme over dynamic encrypted cloud data (TRQED), which supports faster-than-linear range queries and protects single-dimensional privacy. Then, we discuss the defects of TRQED in terms of privacy-preservation. We modify the framework of the system by adopting a two-server model and put forward a safer range query scheme, called TRQED $^{+}$ + . By newly designed secure node query (SNQ) and secure point query (SPQ), we propose the perturbation-based oblivious R-tree traversal (ORT) operation to preserve both path pattern and stronger single-dimensional privacy. Finally, we conduct comprehensive experiments on real-world datasets and perform comparisons with existing works to evaluate the performance of the proposed schemes. Experimental results show that our TRQED and TRQED $^+$ + surpass the state-of-the-art methods in privacy-preservation level and efficiency. [ABSTRACT FROM AUTHOR]

Finding the fastest path in the time-dependent road network is time consuming because its problem complexity is $\Omega (T(|V|\log |V|+|E|))$ Ω (T (| V | log | V | + | E |)) , where $T$ T is the size of the result's time-dependent function, $|V|$ | V | and $|E|$ | E | are the number of vertices and edges. There are three kinds of fastest path problems: SSFP (Single-Staring Time Fastest Path) that has a fixed departure time, ISFP (Interval-Staring Time Fastest Path) that selects the best departure time from an interval, and FPP (Fastest Path Profile) that returns the travel time of the entire time domain. In this paper, we aim to answer these three queries in time-dependent road network faster by extending the 2-hop labeling approach, which is fast in answering shortest distance query in the static graph. However, it is hard to construct index for SSFP and ISFP because there are $|\mathcal {T}|$ | T | and $|\mathcal {T}|^2$ | T | 2 possible time points and intervals, where $\mathcal {T}$ T is the time domain. Therefore, we first propose the time-dependent hop-labeling for FPP, then provide the specific optimizations for SSFP and ISFP query answering. Moreover, it is both time and space consuming to build an index in a large time-dependent graph, so we partition road network into smaller sub-graphs and build indexes within and between the partitions. Furthermore, we propose an online approximation technique AT-Dijkstra and a bottom-up compression method to further reduce the label size, save construction time and speedup query answering. Experiments on real world road network show that our approach outperforms the state-of-art fastest path index approaches and can speed up the query answering by hundreds of times. [ABSTRACT FROM AUTHOR]

Keyword search has been widely studied to retrieve relevant substructures from graphs for a given set of keywords. However, existing well-studied approaches aim at finding compact trees/subgraphs containing the keywords, and ignore a critical measure, density, to represent how strongly and stably the keyword nodes are connected in the substructure. In this paper, given a set of keywords $Q = \lbrace w_1, w_2, \ldots, w_l\rbrace$ Q = { w 1 , w 2 ,... , w l } , we study the problem of finding a cohesive subgraph containing $Q$ Q with high density and compactness from a graph $G$ G . We model the cohesive subgraph based on a carefully chosen $k$ k -truss model, and formulate the problem of finding cohesive subgraphs for keyword queries as minimal dense truss search problem, i.e., finding minimal subgraph that maximizes the trussness covering $Q$ Q . However, unlike $k$ k -truss based community search that can be efficiently done based on the local search from a given set of nodes, minimal dense truss search for keyword queries is a nontrivial task as the subset of keyword nodes to be included in the retrieved substructure is previously unknown. To tackle this problem, we first design a novel hybrid KT-Index to keep the keyword and truss information compacly, and then propose an efficient algorithm that carries the search on KT-Index directly to find the dense truss with the maximum trussness $G_{den}$ G d e n without repeated accesses to the original graph. Then, we develop a novel refinement approach to extract minimal dense truss from the dense truss $G_{den}$ G d e n , by checking each node at most once based on the anti-monotonicity property derived from $k$ k -truss, together with several optimization strategies including batch based deletion, early-stop based deletion, and local exploration. Moreover, we also extend the proposed method to deal with the top- $r$ r search. Extensive experimental studies on real-world networks validated the effectiveness and efficiency of our approaches. [ABSTRACT FROM AUTHOR]

This paper examines the average age minimization problem where only a fraction of the network users can transmit simultaneously over unreliable channels. Finding the optimal scheduling scheme, in this case, is known to be challenging. Accordingly, the Whittle’s index policy was proposed in the literature as a low-complexity heuristic to the problem. Although simple to implement, characterizing this policy’s performance is recognized to be a notoriously tricky task. In the sequel, we provide a new mathematical approach to establish its optimality in the many-users regime for specific network settings. Contrary to previous works in the literature that use restrictive mathematical assumptions, which can be challenging to verify, our novel approach is based on intricate techniques and it is free of any strong mathematical assumptions. These findings showcase that the Whittle’s index policy has analytically provable asymptotic optimality for the AoI minimization problem. Finally, we lay out numerical results that corroborate our theoretical findings and demonstrate the policy’s notable performance in the many-users regime. [ABSTRACT FROM AUTHOR]

The zero capacity region for hexagonal $(d,k)$ run-length constraints is known for many, but not all, $d$ and $k$. The pairs $(d,k)$ for which it has been unproven whether the capacity is zero or positive consist of: (i) $k=d+2$ when $d\ge 2$ ; (ii) $k=d+3$ when $d \ge 1$ ; (iii) $k=d+4$ when either $d=4$ or $d$ is odd and $d \ge 3$ ; and (iv) $k=d+5$ when $d=4$. Here, we prove that the capacity is zero for all of case (i), and for case (ii) whenever $d \ge 7$. The method used in this paper is to reduce an infinite search space of valid labelings to a finite set of configurations that we exhaustively examine using backtracking. In Part II of this two-part series, we use automated procedures to prove that the capacity is zero in case (i) when $2 \le d \le 9$ , in case (ii) when $3 \le d \le 11$ , and in case (iii) when $d \in \{ 4,5,7,9 \}$ , and that the capacity is positive in case (ii) when $d \in \{1,2\}$ , in case (iii) when $d = 3$ , and in case (iv). Thus, the only remaining unknown cases are now when $k=d+4$ , for any odd $d \ge 11$. [ABSTRACT FROM AUTHOR]

This paper proposes a new method of constructing compact fully-connected Quasi-Cyclic Low Density Parity Check (QC-LDPC) codes with girth $g$ = 8, 10, and 12. The originality of the proposed method is to impose constraints on the exponent matrix P to reduce the search space drastically. For a targeted lifting degree of $N$ , the first step of the method is to sieve the integer ring $\mathbb {Z}_{N}$ to make a particular sub-group with specific properties to construct the second column of P (the first column being filled with zeros). The remaining columns of P are determined recursively as multiples of the second column by adapting the sequentially multiplied column (SMC) method whereby a controlled greedy search is applied at each step. The codes constructed with the proposed semi-algebraic method show lengths that can be significantly shorter than their best counterparts in the literature. [ABSTRACT FROM AUTHOR]

The fundamental limits of private information retrieval (PIR) with unknown cache prefetching at the user are investigated in this paper. To this end, a novel random linear combination (RLC)-based PIR scheme that can solve the basic PIR problem and its variation is proposed. The proposed scheme is based on random coding approach and achieves the capacity of the basic PIR asymptotically. Then, we investigate PIR with unknown cache prefetching (PIRC) problem at different cache-to-file size ratio. Specifically, we propose RLC-based PIRC method, which prefetches RLC-based side information and leverages them to retrieve desired information at small download cost. Furthermore, by applying time and memory sharing on the proposed RLC-based PIRC, RLC-based basic PIR and some other known approach in literature, we derive the achievable normalized download cost bound of PIRC. The derived achievable bound outperforms the existing bound in literature and the case study provides numerical results that verifies it. [ABSTRACT FROM AUTHOR]

In this paper, the concept of opportunistic bits (OBs) is developed in short-packet communications and investigated from a finite blocklength perspective. In the OB-based transmission, the data unit of a packet is divided into two parts: OBs and conventional bits (CBs). The OBs are not physically transmitted but used to indicate the index of the time slot (TS) when the packet containing CBs is transmitted. The loading of a bulk of OB-based packets into multiple TSs can be modelled as a Repeated Balls-into-Bins process with a multi-queue storage. If the bulk is not large enough, certain combination(s) of OBs will not appear, which leaves certain TS(s) empty and hence reduces the TS load efficiency. To evaluate the OB-based transmission performance, we formulate its maximal payload rate and TS load efficiency. With the aid of these two formulations, the energy gain, the goodput, and the latency of OB-based short-packet communications are derived and obtained in analytical forms. For achieving further insights, illustrative numerical results on the resource utilisation efficiency and the performance not only substantiate the advantages of the OB-based transmission over the conventional but also provide useful tools and specifications for its design in massive short-packet communications. [ABSTRACT FROM AUTHOR]

We consider multi-access coded caching problem introduced by Hachem et.al., where each user has access to $L$ neighboring caches in a cyclic wrap-around fashion. We focus on the deterministic schemes for a specific class of multi-access coded caching problem based on the concept of Placement Delivery Array (PDA). We construct new PDAs which specify the delivery scheme for the specific class of multi-access coded caching problem discussed in this paper. For the proposed scheme, the coding gain is larger than that of the state-of-the-art for some regimes while the sub-packetization level varies only linearly with the number of users. Hence, we achieve a lower transmission rate with the least sub-packetization level compared to the existing schemes. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel generalized space-code index modulation (GSCIM) scheme for spectrum-efficient and energy-saving transmission. In our proposed scheme, the input information bits are transmitted not only by modulated symbols, but also by the activated transmit antennas pattern and the selected spreading code patterns for the in-phase and quadrature components. Due to the increase of the index dimension, more information bits can be implicitly transmitted, which can improve energy efficiency and have a higher data rate compared with spatial modulation (SM), generalized SM (GSM), generalized CIM-aided SM (GCIM-SM) and CIM-aided quadrature spatial modulation (CIM-QSM). In order to further reduce the complexity of despreading-based maximum likelihood (ML) detection, we propose an enhanced low-complexity detector that can achieve near-ML error performance. An analytical upper bound on the average bit error probability associated with the optimal ML detection is derived, which is verified by simulation results. Simulation results also show that the proposed GSCIM scheme outperforms SM, GSM, GCIM-SM and CIM-QSM schemes in terms of error performance. [ABSTRACT FROM AUTHOR]

Linkages between science and technology have been extensively studied using nonpatent literature citations or author-inventor matching. These methods suffer from limitations, such as the lack of citations to relevant documents or challenges with the disambiguation of author–inventor linkages. To mitigate these limitations, this paper uses Latent Dirichlet Allocation to create topic-based linkages between publications and patents based on the semantic content in the documents. The approach allows for the detection of topical overlap between patent and scientific publications, highlighting topical areas shared by research and application. Using a case study on “Taxol,” a cancer drug, with in total 26 475 documents retrieved from EuropePMC database the study illustrates the performance of the approach. The study offers qualitative and quantitative support that the approach is valuable in detecting patent and publication linkages. [ABSTRACT FROM AUTHOR]

We study the stability of low-density parity-check codes under blockwise or bitwise maximum a posteriori decoding, where transmission takes place over a binary-input memoryless output-symmetric channel. Our study stems from the consideration of constructing universal capacity-achieving codes under low-complexity decoding algorithms, where universality refers to the fact that we are considering a family of channels with equal capacity. Consider, e.g., the right-regular sequence by Shokrollahi and the heavy-tail Poisson sequence by Luby et al. Both sequences are provably capacity-achieving under belief propagation decoding when transmission takes place over the binary erasure channel. In this paper we show that many existing capacity-achieving sequences of low-density parity-check codes are not universal under belief propagation decoding. We reveal that the key to showing this non-universality result is determined by the stability of the underlying codes. More concretely, for an ordered and complete channel family and a sequence of low-density parity-check code ensembles, we determine a stability threshold associated with them, which gives rise to a sufficient condition under which the sequence is not universal under belief propagation decoding. Moreover, we show that the same stability threshold applies to blockwise or bitwise maximum a posteriori decoding as well. We demonstrate how the stability threshold can determine an upper bound on the corresponding blockwise or bitwise maximum a posteriori threshold, revealing the operational significance of the stability threshold. [ABSTRACT FROM AUTHOR]

Consider a massive random access scenario in which a small set of $k$ active users out of a large number of $n$ potential users need to be scheduled in $b\ge k$ slots. What is the minimum common feedback to the users needed to ensure that scheduling is collision-free? Instead of a naive scheme of listing the indices of the $k$ active users in the order in which they should transmit, at a cost of $k\log (n)$ bits, this paper shows that for the case of $b=k$ , the rate of the minimum fixed-length common feedback code scales only as $k \log (e)$ bits, plus an additive term that scales in $n$ as $\Theta (\log \log (n))$ for fixed $k$. If a variable-length code can be used, assuming uniform activity among the users, the minimum average common feedback rate still requires $k \log (e)$ bits, but the dependence on $n$ can be reduced to $O(1)$. When $b>k$ , the number of feedback bits needed for collision-free scheduling can be significantly further reduced. Moreover, a similar scaling on the minimum feedback rate is derived for the case of scheduling $m$ users per slot, when $k \le mb$. The problem of constructing a minimum collision-free feedback scheduling code is connected to that of constructing a perfect hashing family, which allows practical feedback scheduling codes to be constructed from perfect hashing algorithms. [ABSTRACT FROM AUTHOR]

This paper investigates a comprehensive optimization method of determining the size and location of dynamic voltage restorers (DVRs) in distribution network considering customers’ demand for sag mitigation. The objective is to minimize the investment of DVRs subject to customers’ satisfaction. In the objective function, the unit price per kVA of DVR was described by a continuous function of the capacity to calculate the investment. In the constraints, a mitigation expectation index (MEI) was proposed to assess the customers’ demand for mitigation. The MEI indicates the proportion among all sag events affecting customers, which were expected to be mitigated by the customers. It is represented by the cumulative probability of residual voltage of sag events. To improve the computational efficiency, the binary encoding for the locations and real encoding for the output voltage of DVRs are combined as chromosomes in multiple population Genetic Algorithm (MPGA). The proposed method was testified with the IEEE 33 bus distribution system with different sensitive loads. Optimal results were obtained to satisfy different customers’ demand for sag mitigation efficiently. [ABSTRACT FROM AUTHOR]

This paper proposes a distributed frequency control method for an off-grid inverter-based networked microgrid system (NMS) with loads, renewable generators and energy storage devices (ESDs). The frequency regulation problem is formulated as a model predictive control (MPC) problem that aims to maintain the supply-demand power balance within each microgrid and scheduled net power interchange among connected microgrids at minimal regulation costs. The charging/discharging efficiencies as well as energy capacities of ESDs, and constraints on bus voltages are also considered. The proposed MPC problem is solved by a distributed projection-based algorithm via information sharing between adjacent buses. The effectiveness of the proposed method is validated by simulations implemented in Matlab/Simulink. [ABSTRACT FROM AUTHOR]

This paper presents signal processing methods to enhance the energy vs. accuracy trade-off of in-memory computing (IMC) architectures. First, an optimal clipping criterion (OCC) for signal quantization is proposed in order to minimize the precision of column analog-to-digital converters (ADCs) at iso-accuracy. For a Gaussian distributed signal, the OCC is shown to reduce the column ADC precision requirements by 3 bits at a signal-to-quantization noise ratio (SQNR) of $\text{22.5}\,dB$ over the commonly used full range (FR) quantizer. Next, the input-sliced weight-parallel (ISWP) IMC architecture is presented as a generalization of the popular bit-serial bit-parallel (BSBP) architecture. Quantization noise analysis of the ISWP indicates that its accuracy is comparable to BSBP while providing an order-of-magnitude reduction in energy consumption due to fewer array invocations and smaller ADC precision. Combining OCC and ISWP noise analysis, we map popular DNNs such as VGG-9 (CIFAR-10), ResNet-18 (CIFAR-10), and AlexNet (ImageNet) on a OCC-enabled ISWP architecture and show a reduction in energy consumption by an order-of-magnitude at iso-accuracy over the BSBP architecture that employs FR-based ADCs. [ABSTRACT FROM AUTHOR]

Objective: A tendon-transfer is a reconstructive orthopedic surgery where tendons are re-routed from a non-functioning muscle and attached a functioning muscle. Prior work has shown that using a passive implanted device in the ECRL-to-FDP tendon-transfer surgery significantly improves hand grasping function. However, it is still unclear how hand-function improvement, measured by finger joint range of motion and torque, is dependent on the implant’s geometry and location within the tendon network. This paper presents a genetic algorithm that determines the device’s optimal geometry and location. Methods: Hand biomechanical simulation platform was developed to model hand function and also model the tendon-transfer surgery with and without the implant. Finger kinematics and joint torque were used to develop three unique objective functions to optimize the implant’s parameters. Results: The optimized device resulted in an 11X increase in finger kinematics with only a 0.9% decrease in joint torque when compared with the biomechanical function enabled by the current suture-based surgery. Conclusion: Designing implantable devices that modify musculoskeletal function is challenging. Factors like tendon routing and joint kinematics create a complex nonlinear system when considering biomechanical function. A genetic algorithm is an effective tool to tackle these nonlinear landscapes to produce optimized designs. Significance: The state-of-the-art surgical procedure to repair high median-ulnar nerve palsy leads to poor hand function and severely limits the patient’s ability to perform activities of daily life. This work provides a method for defining relevant objective functions for hand biomechanical function and then uses those objective functions with genetic algorithms to optimize the geometry of an orthopedic implant across multiple variables. The achieved biomechanical function is significantly better than hand function enabled by current surgical procedure. [ABSTRACT FROM AUTHOR]

Battery-based Energy Storage Transportation (BEST) is the transportation of modular battery storage systems via train cars or trucks representing an innovative solution for a) enhancing Variable Renewable Energy (VRE) utilization and load shifting, and b) providing a potential alternative for managing transmission congestions. This paper focuses on point b) and proposes a long-term transmission-planning model coordinated with both stationary and mobile storage units. The planning-problem objective function minimizes the total system cost, i.e., the sum of i) the investment cost of candidate transmission lines, stationary and mobile storage systems, and ii) the operation cost, including conventional generating units fuel consumption, load shedding penalty and BEST transportation costs. An alternative approach for BEST vehicle scheduling problem is implemented. The contribution lies in the accomplishment of the spatial-temporal scheduling of the mobile storage units by including the Number-of-nonzero mathematical function in the optimization model set of constraints instead of using additional binary variables as generally accomplished. The identification of either storage systems optimal location, or both optimal location and size of storage systems is also allowed. BEST usefulness is analyzed and discussed for a test-system emulating a reals system in China-Northwestern-grid with high VRE penetration divided in five regional areas, of which the most promising one for BEST implementation is identified. [ABSTRACT FROM AUTHOR]

Among various array configurations, superdirective beamforming based on linear differential arrays has attracted much attention. It is well known that its directivity performance degrades at higher frequencies due to the limitation of finite difference approximation, and its robustness deteriorates due to the mismatch of practical systems. In this paper, we develop a wavenumber-domain superdirective beamforming for endfire arrays, an alternative way of phase mode beamforming that cannot be applied directly to linear arrays. Here, “wavenumber-domain” means the spatial derivatives are calculated in the wavenumber domain through multiplication operations. An important feature of proposed method is that it provides a novel way to obtain the higher order derivatives from the reconstructed sound field utilizing all sensors of array, which is valid when the Nyquist criterion is satisfied, resulting in a broadband frequency-independent beamformer. On the other hand, since the proposed $N\rm {th}$ -order superdirective beamformer has no upper limit of number of sensors, its robustness at lower frequencies can be enhanced through increasing the number of sensors and using an optimum truncation parameter which plays a role to remove small singular values sensitive to the mismatch of array. Although it is demonstrated that the proposed method and the weighted least-squares optimization method lead to almost identical performances, the main advantage of the proposed method is that an optimum truncation parameter determined by the experiment is adopted to increase the robustness of beamformers, where the high sensitivity of the higher eigenbeams to random errors is exploited. [ABSTRACT FROM AUTHOR]

Since its introduction in 2018, EPIC-KITCHENS has attracted attention as the largest egocentric video benchmark, offering a unique viewpoint on people’s interaction with objects, their attention, and even intention. In this paper, we detail how this large-scale dataset was captured by 32 participants in their native kitchen environments, and densely annotated with actions and object interactions. Our videos depict nonscripted daily activities, as recording is started every time a participant entered their kitchen. Recording took place in four countries by participants belonging to ten different nationalities, resulting in highly diverse kitchen habits and cooking styles. Our dataset features 55 hours of video consisting of 11.5M frames, which we densely labelled for a total of 39.6K action segments and 454.2K object bounding boxes. Our annotation is unique in that we had the participants narrate their own videos (after recording), thus reflecting true intention, and we crowd-sourced ground-truths based on these. We describe our object, action and anticipation challenges, and evaluate several baselines over two test splits, seen and unseen kitchens. We introduce new baselines that highlight the multimodal nature of the dataset and the importance of explicit temporal modelling to discriminate fine-grained actions (e.g., ‘closing a tap’ from ‘opening’ it up). [ABSTRACT FROM AUTHOR]

Analytical modeling of Age of Information (AoI) and Peak AoI (PAoI) has recently drawn a lot of attention in the context of quantitative assessment of information freshness in status update systems. In this paper, we study a probabilistically preemptive bufferless M/PH/1/1 queue fed with information update packets from $N$ separate information sources for which a new information packet arrival from source- $m$ is allowed to preempt a packet from source- $n$ in service, with a probability depending on $n$ and $m$. To make the model even more general than the existing ones, we assume a distinct phase-type (PH-type) service time distribution, a distinct packet error and retransmission probability, for each of the information sources. Using sample path arguments and the theory of Markov Fluid Queues (MFQ), the exact distributions of the AoI and PAoI are numerically obtained for each of the sources. Numerical examples are provided to demonstrate the impact of various system parameters on AoI performance. In the context of a two-source system, we present a methodology on how to optimally choose the preemption probabilities and packet generation rates so as to minimize certain AoI-oriented cost functions. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surface (RIS) has recently received extensive research interest due to its capability to intelligently change the wireless propagation environment. For RIS-aided wireless communications in frequency division duplex (FDD) mode, channel feedback at the user equipment (UE) is essential for the base station (BS) to acquire the downlink channel state information (CSI). In this paper, a dimension reduced channel feedback scheme is proposed to reduce the channel feedback overhead by exploiting the single-structured sparsity of BS-RIS-UE cascaded channel. Since different UEs share the same sparse BS-RIS channel but have their respective RIS-UE channels, there are only limited non-zero column vectors in the BS-RIS-UE cascaded channel matrix, and different UEs share the same indexes of the non-zero columns. Thus, the downlink CSI can be decomposed into user-independent channel information (i.e., the indexes of non-zero columns) and user-specific channel information (i.e., the non-zero column vectors), where the former for all UEs can be fed back by only one UE, while the latter can be fed back with a fairly low overhead by different UEs, respectively. Simulation results show that, compared with the conventional method, the proposed scheme can reduce channel feedback overhead by more than 80% for RIS-aided wireless communications. [ABSTRACT FROM AUTHOR]

In this paper, we propose a general carrier index assisted dual-mode differential chaos shift keying with full mapping (GCI-DM-DCSK-FM) system, where a pair of distinguishable modem-mode signals is designed with the aid of general carrier index modulation. Specifically, the selected and unselected subcarriers are used to carry differential chaos shift keying (DCSK) and quadrature chaos shift keying (QCSK) signals, respectively, thereby obtaining higher data rate and spectral efficiency. To tackle the issue of discarding the subcarrier activation pattern (SAP), an effective full mapping method is proposed for the GCI-DM-DCSK-FM system to harvest better bit error rate (BER) performance and higher data rate. Moreover, a noise decontamination method is designed for the GCI-DM-DCSK-FM system to enhance the BER performance. To confirm the validness for our proposed systems, we derive the BER expressions of the GCI-DM-DCSK-FM system over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels. Finally, plenty of simulation results show the excellent BER performance of the GCI-DM-DCSK-FM system. [ABSTRACT FROM AUTHOR]

Recovering missing values in time series is critical when performing time series analysis. And the blackouts issue studied in this paper, described as losing all the data during a certain period, is among the most urgent issues due to its devastating impact on service quality, and is challenging because of the absence of coevolving data sequences for reference. As a result, many existing approaches that rely on data from other coevolving sequences for missing value recovery are infeasible in handling blackouts. To address the issue, this work proposes a novel Hankel matrix factorization approach, HKMF-T, to recover missing values during blackouts for tagged time series, where a tagged time series consists of a data sequence and a corresponding tag sequence. Motivated by real-world observations, HKMF-T decomposes the data sequence into two components: 1) an internal, slowly-varying smooth trend, and 2) external impacts indicated by the tag sequence. By transforming a partially observed data sequence into a corresponding Hankel matrix, we learn the above two components and estimate the missing values under a unified framework of Hankel matrix factorization. Extensive experiments are conducted to evaluate the practical performance of HKMF-T on real-world data sets. And the results suggest HKMF-T outperforms the baseline approaches for blackouts with long durations. [ABSTRACT FROM AUTHOR]

A complete characterization for the restricted isometry constant (RIC) bounds on $\delta _{{{ tk}}}$ for all $ {t}>0$ is an important problem on recovery of sparse signals with prior support information via weighted $\ell _{{p}}$ -minimization ($0 < {p} \leqslant 1$). In this paper, new bounds on the restricted isometry constants $\delta _{{{ tk}}}$ ($0 < {t} < \frac {4}{3}{d}$), where $d$ is a key constant determined by prior support information, are established to guarantee the sparse signal recovery via the weighted $\ell _{{p}}$ minimization in both noiseless and noisy settings. This result fills a vacancy on $\delta _{{{ tk}}}$ with $0 < {t} < \frac {4}{3}{d}$ , compared with previous works on $\delta _{{{ tk}}}$ (${t} \geqslant \frac {4}3{d}$). We show that, when the accuracy of prior support estimate is at least 50%, the new recovery condition in terms of $\delta _{{{ tk}}}$ ($0 < {t} < \frac {4}{3}{d}$) via weighted $\ell _{1}$ minimization is weaker than the condition required by classical $\ell _{1}$ minimization without weighting. Our weighted $\ell _{1}$ minimization gives better recovery error bounds in noisy setting. Similarly, the new recovery condition in terms of $\delta _{{{ tk}}}$ ($0 < {t} < \frac {4}{3}{d}$) is extended to weighted $\ell _{{p}}$ ($0 < {p} < 1$) minimization, and it is also weaker than the condition obtained by standard non-convex $\ell _{{p}}$ ($0 < {p} < 1$) minimization without weighting. Numerical illustrations are provided to demonstrate our new theoretical results. [ABSTRACT FROM AUTHOR]

The paper deals with linear information inequalities valid for entropy functions induced by discrete random variables. Specifically, the so-called conditional Ingleton inequalities are in the center of interest: these are valid under conditional independence assumptions on the inducing random variables. We discuss five inequalities of this particular type, four of which has appeared earlier in the literature. Besides the proof of the new fifth inequality, simpler proofs of (some of) former inequalities are presented. These five information inequalities are used to characterize all conditional independence structures induced by four discrete random variables. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of multiple graph matching (MGM) by considering both offline batch mode and online setting. We explore the concept of cycle-consistency over pairwise matchings and formulate the problem as finding optimal composition path on the supergraph, whose vertices refer to graphs and edge weights denote score function regarding consistency and affinity. By our theoretical study we show that the offline and online MGM on supergraph can be converted to finding all pairwise shortest paths and single-source shortest paths respectively. We adopt the Floyd algorithm and shortest path faster algorithm (SPFA) , to effectively find the optimal path. Extensive experimental results show our methods surpass state-of-the-art MGM methods, including CAO , MISM , IMGM , and many other recent methods in offline and online settings. Source code will be made publicly available. [ABSTRACT FROM AUTHOR]

Underwater acoustic sensor networks (UW-ASNs) have received increasing attention in the civil and military fields. However, due to the unique features of the underwater environment, designing a suitable media access control (MAC) protocol for UW-ASNs is an immense challenge. While orthogonal frequency division multiple access (OFDMA) is a multiple access technology based on orthogonal frequency division multiplexing (OFDM), allocating different subchannels to different users for parallel transmission. In this paper, we propose a traffic load-aware OFDMA-based MAC protocol for UW-ASNs, called TLAO-MAC, that can suit the operational requirements of distributed underwater sensor networks. It uses the exchange of control packets to collect data transmission requests and update the channel resource list. Neighboring nodes rely on receiving nodes to conduct channel negotiation and resource allocation in a distributed manner. In addition, we define the channel busyness index to sense the dynamic traffic load in distributed networks. The proposed TLAO-MAC includes two key schemes: an adaptive channel grouping algorithm based on channel busyness, and a distributed subcarrier and power allocation algorithm. By adaptively adjusting the channel grouping in consideration of the dynamics of the traffic load, TLAO-MAC allows simultaneous transmission between neighboring nodes and avoids conflict in the data channel. Under the premise of meeting the transmission rate requirement of the sender, the transmission power is saved to the greatest extent. The simulation results show that TLAO-MAC can improve network goodput and reduce end-to-end delay, showing better adaptability in distributed networks. [ABSTRACT FROM AUTHOR]

This paper focuses on the issue of achieving transmit diversity for the multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system working with quadrature index modulation (QIM). Inspired by the ideas of quadrature spatial modulation (QSM) and quadrature space-frequency index modulation (QSF-IM), parts of the space-frequency resource units in each resource block (RB) of the MIMO-OFDM system are activated twice independently to send the in-phase and quadrature components of a space-frequency code, respectively, to achieve the second order transmit diversity. Thus the proposed scheme is called space-frequency coded QIM (SFC-QIM). The SFC-QIM scheme allows for a linear-complexity maximum likelihood (ML) receiver, which benefits from the orthogonality between the real and imaginary parts of the symbols in the SFC codewords. Owing to obtaining higher diversity order, simulation results of bit error rate (BER) performance demonstrate that the new SFC-QIM scheme outperforms some existing IM schemes in both independent and identically distributed (i.i.d.) and correlated Rayleigh fading channels. [ABSTRACT FROM AUTHOR]

In this paper, a novel differential space-time block coded spatial modulation (differential STBC-SM) is proposed for uplink multi-user massive multiple-input multiple-output (MIMO) communications, which combines the concept of differential coding and STBC-SM to enhance the diversity benefits in the absence of the channel state information (CSI). The transmission structure of the proposed system is on a block basis, where each block contains two sub-blocks. More specifically, the first sub-block only conveys amplitude and phase modulation (APM) symbol bits, since its transmit antennas (TAs) obey a pre-designed activation pattern, which do not carry any information bit. For the second sub-block, the input bits are modulated to STBC-SM matrices, which are then differentially coded between two adjacent sub-blocks. Moreover, a novel block-by-block based non-coherent detector is presented. Finally, we derive an upper bound on the average bit error probability (ABEP) by using the moment generating function (MGF). Our simulation results show that the proposed differential STBC-SM transmission structure is able to acquire considerable bit error rate (BER) performance improvements compared to both the conventional differential spatial modulation (DSM) and differential Alamouti schemes. [ABSTRACT FROM AUTHOR]

Given a geo-textual dataset $\mathbb {O}$ O , a set $\varphi$ φ of keywords, a query object $q \in \mathbb {O}$ q ∈ O , and an integer $k$ k , a reverse top- $k$ k keyword-based location query returns the influence zone $\mathcal {R}$ R of $q$ q such that $q$ q belongs to the result of a top- $k$ k spatial keyword query with query keywords $\varphi$ φ and any location in $\mathcal {R}$ R as arguments. For a query object $q$ q , the influence zone of $q$ q varies for different keywords $\varphi$ φ . Users may be interested in identifying the maximum influence zone of the query object. To this end, in this paper, we study the problem called MaxiZone that finds the keyword set maximizing the influence zone of a specified query object. The MaxiZone problem has many real-life applications, e.g., a business owner would like to identify the maximum influence zone so as to attract as many customers as possible. A straightforward way to tackle the MaxiZone problem is to compute the influence zone for every candidate keyword set. Obviously, this is infeasible if there are a large number of candidate keyword sets. We propose a more efficient index-centric algorithm together with a series of optimizations as well as a sampling-based algorithm, to facilitate the query processing. Moreover, we extend the proposed algorithms to address a variant of MaxiZone problem called $\tau$ τ -MaxiZone problem, which finds top- $\tau$ τ keyword sets having the maximum influence zones. Extensive empirical study using real-world datasets demonstrates the effectiveness and efficiency of our proposed algorithms. [ABSTRACT FROM AUTHOR]

It is well known that the capacity region of an average transmit power constrained Gaussian Broadcast Channel (GBC) with independent noise realizations at the receivers is enlarged by the presence of causal noiseless feedback. When the noise variances at the receivers are identical, even passive feedback via independent memoryless Gaussian links can lead to a capacity region enlargement. The last fact remains true even when the feedback noise variance is very high, and available only from one of the receivers. While such capacity enlargements are feasible for several other feedback models in the Gaussian BC setting, it is also known that feedback does not change the capacity region for physically degraded broadcast channels. In this paper, we consider a two user GBC with independent noise realizations at the receivers, where the feedback links from the receivers are corrupted by independent additive Gaussian noise processes. We investigate the set of four noise variances, two forward and two feedback, for which no capacity enlargement is possible. A sharp characterization of this region is derived, i.e., any quadruple outside the presented region will lead to a capacity enlargement, whereas quadruples inside will leave the capacity region unchanged. Our results lead to the conclusion that when the forward noise variances are different, too noisy a feedback from one of the receivers alone is not always beneficial for enlarging the capacity region, be it from the stronger user or the weaker one, in sharp contrast to the case of equal forward noise variances. [ABSTRACT FROM AUTHOR]

Versatile Video Coding (VVC) is the latest video coding standard jointly developed by ITU-T VCEG and ISO/IEC MPEG. In this paper, technical details and experimental results for the VVC block partitioning structure are provided. Among all the new technical aspects of VVC, the block partitioning structure is identified as one of the most substantial changes relative to the previous video coding standards and provides the most significant coding gains. The new partitioning structure is designed using a more flexible scheme. Each coding tree unit (CTU) is either treated as one coding unit or split into multiple coding units by one or more recursive quaternary tree partitions followed by one or more recursive multi-type tree splits. The latter can be horizontal binary tree split, vertical binary tree split, horizontal ternary tree split, or vertical ternary tree split. A CTU dual tree for intra-coded slices is described on top of the new block partitioning structure, allowing separate coding trees for luma and chroma. Also, a new way of handling picture boundaries is presented. Additionally, to reduce hardware decoder complexity, virtual pipeline data unit constraints are introduced, which forbid certain multi-type tree splits. Finally, a local dual tree is described, which reduces the number of small chroma intra blocks. [ABSTRACT FROM AUTHOR]

Efficient representation and coding of fine-granular motion information is one of the key research areas for exploiting inter-frame correlation in video coding. Representative techniques towards this direction are affine motion compensation (AMC), decoder-side motion vector refinement (DMVR), and subblock-based temporal motion vector prediction (SbTMVP). Fine-granular motion information is derived at subblock level for all the three coding tools. In addition, the obtained inter prediction can be further refined by two optical flow-based coding tools, the bi-directional optical flow (BDOF) for bi-directional inter prediction and the prediction refinement with optical flow (PROF) exclusively used in combination with AMC. The aforementioned five coding tools have been extensively studied and finally adopted in the Versatile Video Coding (VVC) standard. This paper presents technical details of each tool and highlights the design elements with the consideration of typical hardware implementations. Following the common test conditions defined by Joint Video Experts Team (JVET) for the development of VVC, 5.7% bitrate reduction on average is achieved by the five tools. For test sequences characterized by large and complex motion, up to 13.4% bitrate reduction is observed. Additionally, visual quality improvement is demonstrated and analyzed. [ABSTRACT FROM AUTHOR]

Obstructive sleep apnea is a common sleep disorder with a high prevalence and often accompanied by significant snoring activity. To diagnose this condition, polysomnography is the standard method, where a neck microphone could be added to record tracheal sounds. These can then be used to study the characteristics of breathing, snoring or apnea. In addition cardiac sounds, also present in the acquired data, could be exploited to extract heart rate. The paper presents new algorithms for estimating heart rate from tracheal sounds, especially in very loud snoring environment. The advantage is that it is possible to reduce the number of diagnostic devices, especially for compact home applications. Three algorithms are proposed, based on optimal filtering and cross-correlation. They are tested firstly on one patient presenting significant pathology of apnea syndrome, with a recording of 509 min. Secondly, an extension to a database of 16 patients is proposed (16 hours of recording). When compared to a reference ECG signal, the final results obtained from tracheal sounds reach an accuracy of 81% to 98% and an RMS error from 1.3 to 4.2 bpm, according to the level of snoring and to the considered algorithm. [ABSTRACT FROM AUTHOR]

This paper presents a two-stage stochastic planning model for transmission systems and distributed energy resources (DERs) considering power system resiliency. The model takes into account both normal and emergency conditions as well as the duration of each condition. The proposed model is formulated as a mixed-integer linear program to minimize the total investment cost of transmission lines and DERs, expected values of generators’ operation cost in normal and emergency situations, and load shedding cost in emergency condition. The emergency scenarios are considered as moderate, severe, and complete damage states, which have different recovery times for transmission assets. The Benders decomposition technique is utilized to solve the optimization problem. Numerical results are demonstrated based on the IEEE 118-bus test system. [ABSTRACT FROM AUTHOR]

In this paper, a coupled interaction matrix is proposed to describe the interactions between line outages and the load shed at buses. The coupled interaction matrix is effectively estimated by the Expectation Maximization algorithm. A highly probabilistic coupled interaction model is further proposed to efficiently generate cascades with both line outages and the load shed based on the coupled interaction matrix and the distribution of initial outages. To mitigate cascading failures, critical links are identified based on the coupled interaction matrix by calculating a comprehensive severity index that considers the consequences of both line outages and the load shed. Simulation results on the IEEE 300-bus system verify the effectiveness of the proposed approach. The cascades generated from the coupled interaction model match the statistics of the original cascades very well. The identified critical links based on the comprehensive severity index enable a proper tradeoff between reducing line outages and reducing the load shed, leading to a better mitigation effect than only considering either line outages or the load shed. [ABSTRACT FROM AUTHOR]

Software-defined Internet-of-Things networking (SDIoT) greatly simplifies the network monitoring in large-scale IoT networks by per-flow sampling, wherein the controller keeps track of all the active flows in the network and samples the IoT devices on each flow path to collect real-time flow statistics. There is a tradeoff between the controller’s sampling preference and the balancing of loads among devices. On the one hand, the controller may prefer to sample some of the IoT devices on the flow path because they yield more accurate flow statistics. On the other hand, it is desirable to sample the devices uniformly so that their energy consumptions and lifespan are balanced. This paper formulates the flow sampling problem in large-scale SDIoT networks by means of a Markov decision process and devises policies that strike a good balance between these two goals. Three classes of policies are investigated: the optimal policy, the state-independent policies, and the index policies (including the Whittle index and a second-order index policies). The second-order index policy is the most desired policy among all: 1) in terms of performance, it is on an equal footing with the Whittle index policy, and outperforms the state-independent policies by much; 2) in terms of complexity, it is much simpler than the optimal policy, and is comparable to state-independent policies and the Whittle index policy; 3) in terms of realizability, it requires no prior information on the network dynamics, hence is much easier to implement in practice. [ABSTRACT FROM AUTHOR]

Shaped polar codes were recently proposed to improve the spectral efficiency of polar coded modulation, based on probabilistic shaping. The key principle for them is to adjust the probability of occurrence of 1’s in each codeword by introducing the shaping bits, which makes the distribution of modulated symbols close to the Gaussian distribution. But, they have a serious problem from a practical viewpoint, since additional polar decoding is required to determine the shaping bits. In this paper, we investigate an algebraic approach to the design of structurally shaped polar codes. We first select a shaping set in an algebraic and systematic way and determine the shaping bits by using simple binary and integer operations without any additional polar decoding. We then propose a method to construct structurally shaped polar codes, and analyze their shaped probability in an approximate way. Finally, we present the encoding and decoding procedures for the proposed shaped polar codes. Numerical results show that the proposed shaping scheme has similar performance than the conventional shaping scheme regardless of whether cyclic redundancy check is employed, while the former can be implemented in an extremely simpler way than the latter. [ABSTRACT FROM AUTHOR]

In this paper, motivated by the framework of diversity-achieving quadrature spatial modulation (DA-QSM), we propose a generalized quadrature space-frequency index modulation (GQSF-IM) transmission scheme for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. The dispersion matrices potentially transmit some combination of each symbol from each antenna at every subcarrier, and their structures lead to desirable coding properties. By setting two well-designed dispersion-matrix sets for both the in-phase (I-) and quadrature (Q-) dimensions, each resource block (RB) of MIMO-OFDM independently selects part of dispersion matrices from each set to modulate the real and imaginary parts of complex symbols, respectively. Thus a simple and systematic method which easily generates dispersion-matrix set with large size is presented. It can be verified that the proposed GQSF-IM scheme subsumes the existing QSF-IM scheme as its special case. Moreover, it can be proved that the GQSF-IM scheme automatically achieves the second order transmit diversity without requiring any parameter or matrix optimization. Owing to obtaining higher transmit diversity order, simulation results of bit error rate (BER) performance show that GQSF-IM outperforms QSF-IM in different channels such as independent and identically distributed (i.i.d.), correlated Rayleigh fading, and Rician channels. Furthermore, GQSF-IM can achieve obvious better BER performance when it combines with interleaving for more diversity gains. [ABSTRACT FROM AUTHOR]

Road garbage recognition and cleanliness assessment are very important for intelligent cleaning of vehicles. However, widely used garbage detection methods cannot provide accurate information to assess cleanliness. Also, only a few contributions are available in the road cleanliness assessment, and they too mainly depend on the category and quantity of garbage. In this paper, deep supervision UNet++ (DUNet++) is proposed to solve the problem of road garbage classification and segmentation, which can directly impact the output of the category of garbage and the occupied ground area. A new, simple and accurate method is established to assess road cleanliness by combining the results of garbage segmentation. Compared with the cleanliness index (CI), the road cleanliness index based on semantic segmentation (CISS) not only considers the road area occupied by different types or categories of the garbage but also considers the difficulty of cleaning them. A road garbage segmentation dataset, which consists of four categories (stones, leaves, sand, and bottles), is collected to train the designed garbage segmentation model, and it has achieved considerable garbage segmentation improvement with an MIoU (Mean Intersection over Union) of $76.73\pm 0.11$. Especially when compared with the state-of-the-art methods, the model we designed has greatly improved the accuracy of garbage segmentation. Experimental results have shown that our road garbage segmentation and cleanliness assessment methods are relatively simple, and can provide accurate road cleanliness information for cleaning vehicles. [ABSTRACT FROM AUTHOR]

This paper deals with the coordinated control of the multiple high-speed train system taking into account the sampled characteristic of the communication information. Considering the inertial lag of the servo motor/braking unit in practical scenarios, a third-order nonlinear model is adopted to capture the dynamics of a train, based on which the coordinated control problem is formulated. By virtue of the back-stepping linearization technique, the sampled-data communication based train coordination is transformed to the stabilization of a linear multiple-input system subject to periodic time-varying input delay. An event-triggering communication framework is constructed to lower the dependence on the communication resource. Furthermore, distributed low-gain feedback control protocols are established that, besides achieving coordination of the train operation, ensure the trains track the predefined train speed profile while avoiding unnecessary information transmission. Numerical experiments are carried out to verify the theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, multidimensional constellation designs of spatial modulated sparse code multiple access (SM-SCMA) systems with arbitrary number of transmit antennas are investigated to improve the system performance. Firstly, the symbol error rate (SER) performance of single-user and multi-user systems under flat independent Rayleigh fading channels is analyzed. It is shown that except for the product distance of the sub-constellation of each antenna, the product of the norm of symbols on each-dimension can affect single-user performance. Then, based on the performance analysis, a symmetric multidimensional constellation (SMC) and a golden-angle-modulation-based constellation (GAMC) are proposed for the general case where the number of transmit antennas is an arbitrary integer, and a low-complexity SMC (LSMC) is proposed for the special case where the number of transmit antennas is a power of two. Finally, the three proposed design schemes are extended to transmit correlated scenarios. Simulation results show that for uplink systems, compared with existing schemes, SMC provides the best SER performance and has no limitation on the number of transmit antennas. When the transmitter has no spatial correlation and the number of transmit antennas is a power of two, LSMC can achieve comparable performance to SMC with reduced computational complexity. For downlink systems, GAMC can obtain a considerable performance gain (up to 3 dB) over other solutions under transmit correlated channels. [ABSTRACT FROM AUTHOR]