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With the rapid development of economic globalization and information technology, the projects undertaken by enterprises are gradually becoming larger and more complex. The multi-project management model has become the norm in enterprise management, and it shows a trend of decentralization in terms of geographical distribution and management environment. This decentralization mainly manifests in the fact that each project has its own private information and benefit objectives and shares limited global resources with other projects during the execution process, forming a decentralized decision-making environment. As an extension of the resource-constrained project scheduling problem, the decentralized resource-constrained multi-project scheduling problem integrates single-project scheduling and global resource coordination allocation in a decentralized decision-making environment with multiple independent decision-makers. Furthermore, when considering global resources as multi-skilled staff, the decentralized multi-project scheduling problem sharing multi-skilled staff studied in this paper is proposed. A two-layer model containing local scheduling and global coordination decision-making is established to describe this problem. A two-layer approach (TLA) is proposed to solve this problem. In the local scheduling layer, a bat algorithm based on forward-backward scheduling (BAFBS) is developed to generate local baseline schedules to minimize the single-project completion time. In the global coordination decision-making layer, a variable neighborhood tabu search algorithm with greedy assignment strategy is designed to resolve global resource conflicts to minimize the multi-project total tardiness cost. Computational experiments are conducted based on the Multi-Project Scheduling Problem LIBrary dataset. The results show that the BAFBS can obtain high-quality local baseline schedules. Compared to the existing decentralized and centralized methods, our proposed TLA can get better solutions on most problem subsets, which proves that our approach can effectively coordinate the allocation of multi-skilled staff among multiple projects.

In practical multi-skilled resource-constrained multi-project management, the activity duration is often affected by some factors (e.g., rework, increased workload), leading to uncertainty. Moreover, multiple projects are often managed under a distributed decision-making environment. To deal with uncertain activity durations in distributed multi-project management with multi-skilled staff, this paper studies a stochastic distributed resource-constrained multi-project scheduling problem with multi-skilled staff (MS-SDRCMPSP). In a distributed decision-making environment, a two-stage model with local scheduling and global coordination stages is established to describe MS-SDRCMPSP. A two-stage algorithm with 12 priority rules (TSA-12PRs) is proposed, these 12 priority rules are composed of 4 activity priority rules and 3 resource priority rules. In the local schedule stage, 4 activity priority rules (PRs) are applied to obtain the local schedule plan. In the global coordination phase, we develop 3 resource PRs based on variable neighborhood search (VNS), of which VNS is used to solve the execution order of conflicting projects, and 3 resource PRs are developed to formulate multi-skilled resource assignment strategies. Based on the multi-skilled instances adapted from benchmark instances, we evaluate the performance of the 12 PRs on different instances. The experiment results show that two PRs among 12 PRs perform better than other PRs in all-size instances. Comparing the two-stage algorithm with better two PRs with other approaches in literatures, we find that our method performs better than other approaches, especially in large-size instances. In addition, further experiments show that our method is more conducive to shortening the CPU runtime on distributed problems than centralized methods.

A novel method for complex amplitude manipulation of spin light is proposed based on a double-layer compact anisotropic metasurface. A new degree of freedom (DOF) is introduced through independently rotating the two layers to achieve a full range control of the amplitude. Then additional full range phase shift is further imparted independently based on the traditional Pancharatnam-Berry (PB) phase mechanism by the global rotation of the meta-atom. As a result, the ability of full range and arbitrary complex amplitude manipulation is achieved on meta-atom level. Time consuming massive geometric parameter searching is avoided in the proposed method, which is beneficial to the complicated metadevice design. Based on this theory, two devices for multi-beam generation and Airy beam deflection are designed and experimentally verified, respectively. The good agreement between the calculated and measured results confirms the advantage of the proposed method. Our findings may trigger great interest in high-performance functional metaoptics devices with compact size in integrated systems.

We investigate the generalized projective synchronization (GPS) control of fractional-order extended Hindmarsh-Rose (FOEHR) neuronal models with transcranial magneto-acoustical stimulation (TMAS) input. This improved neuronal model has advantages in describing the complex firing characteristics of neurons stimulated by alternating current. In this study, a master-slave neuron system consisting of two FOEHR neuronal models is assumed to be subject to uncertain model parameters and unknown external disturbances. To quantify the GPS error, we design a new error variable based on the properties of the fractional-order derivative and construct a related GPS error system. Fuzzy logic systems are introduced to approximate the unknown nonlinear dynamics of the error system. To ensure the synchronous firing rhythms of the master-slave neuron system, an adaptive fuzzy control algorithm is proposed under the Lyapunov approach, in which the adaptive parameters are robust to the estimation errors. By choosing the appropriate design parameters, the proposed control scheme enables the master-slave neuron system to achieve GPS in a finite amount of time and to be resilient to uncertain parameters and unknown disturbances. The simulation results demonstrate that after the designed control inputs are implemented, the states of the slave neuron synchronize with those of the master neuron in specified proportions, and the corresponding synchronization error converges towards an arbitrarily small neighborhood of zero.

With the application of energy storage systems in photovoltaic power generation, the selection and optimal capacity configuration of energy storage batteries at photovoltaic-energy storage stations (PESS) are becoming more and more important. Aiming at the overall economics of the PESS in the scenario of tracking the planning output, a capacity configuration and economic evaluation method of the PESS based on game theory and analytic hierarchy process (AHP) is proposed. Taking the minimum discarded photovoltaic power and the maximum net income of the PESS as objective functions, a comprehensive model of the PESS is built according to the historical data of the PESS. Combined with the characteristics of different electrochemical energy storage batteries, the relationships among the net income of the PESS, the depths of discharge (DODs) and the capacity of the energy storage batteries are analyzed. When the amount of the discarded photovoltaic power is zero, a selection and capacity configuration model of the energy storage batteries based on game theory is established, and the firefly algorithm (FA) is adopted to solve the model. Starting from the comprehensive evaluation indexes of the PESS, the hierarchical analysis structure under different energy storage schemes is discussed, and the AHP is employed to realize the overall economic evaluation of the PESS, in which the weight of the evaluation indexes in different energy storage schemes is calculated by the entropy weight method. The effectiveness and correctness of the proposed method are verified through the simulation analysis of the actual operation data of a certain PESS in China. The simulation results show that the selection and optimal capacity configuration of the energy storage batteries have an important impact on the overall economics of the PESS, and the overall economics of the PESS obtained by three types of electrochemical energy storage batteries is the highest income of 249.5 Million $, which can provide a theoretical basis for the planning of the PESS and has certain engineering application prospects.

The single-switch topologies, e.g., the Class E topology, have the advantages of low component count, no shoot-through problem, simple driving circuit, which make it more suitable for high frequency low/medium-power wireless power transfer (WPT) applications. However, due to the high switch voltage stress, narrow soft switching range, bulky input choke, or ac inductor, its power delivery capability and applications are limited. In order to solve these problems, this article proposed a novel active clamp topology for high cost-performance medium-power WPT systems. The proposed topology offers low component count with no bulky inductor and low switch voltage stress, leading to high power-density, low cost, and compact size, i.e., high cost-performance for WPT applications. And the switch peak voltage can be adjusted and the soft switching operation can be achieved in a wide load range by designing the compensation capacitor and clamp capacitor. In this article, the detailed theoretical analysis and parameter design are discussed and the proposed topology is compared with the existing single-switch topology in terms of voltage stress, cost, and component count. A 120 W and 1 MHz active clamp WPT system is built and a 92.4% system efficiency is achieved with high cost-performance, which validate the feasibility of the proposed topology and the theoretical analysis. [ABSTRACT FROM AUTHOR]

The temporal response of CdZnTe (CZT) detector to $\gamma $ -ray is experimentally studied in this article. Infrared (IR) illumination is utilized to improve the performance of CZT detector. The results show that with no IR illumination operated on the CZT detector, the output signal of the CZT detector appears as a short overshoot process (sharp peak) at the beginning of stable $\gamma $ -ray irradiation. After the sharp peak, a decay process follows, and finally, a stable output of CZT detector is achieved. IR illumination can eliminate the instability of CZT detector under $\gamma $ -ray irradiation, such as the output overshoot of detector (sharp peak) during the transition state. With the increase of IR illumination intensity, the sharp peak disappears gradually and the temporal response of CZT detector follows the intensity of $\gamma $ -ray irradiation without transition state. The fitting time constant of the sharp peak is in good consistency with the typical detrapping lifetime on the order of seconds. The stable current of CZT $\gamma $ -ray detector can be improved by 8.2% due to IR illumination, which can also be explained by the prefilling effects of IR illumination on the defect level. The sharp peak in the temporal response of CZT detector is probably caused by the deep level, related to the Te antisite-related deep donors. The current uncertainty of CZT $\gamma $ -ray detector under IR illumination is smaller than 1.4%, which is small enough to be ignored. The flux rate response of CZT detector can also be improved by IR illumination. This study will provide significant supports for the further application of CZT material in radiation measurements. [ABSTRACT FROM AUTHOR]

The emerging sub-/super-synchronous interactions (S2SI) related stability issues caused by the interactions of doubly fed induction generator (DFIG)-based wind farms and the large-scale ac grids have aroused great concerns. For this particular issue, this article is aimed to fill the gap and propose new time-domain and phasor-domain sub-/super-synchronous impedance models (S2SIM), primarily to disclaim the electro-magnetic stability of the S2SI phenomena. First, the unified dq frame impedance model of the DFIGs have been proposed, including the individual and interactive impact of every control sections, such as the induction machine, the grid-side converter, the rotor-side converter, and the outer dc voltage controller, etc. Then, the more general time-domain S2SIM and phasor-domain shifted frequency S2SIM (SF-S2SIM) have been derived to reveal the electro-magnetic stability mechanism, especially aroused by S2SI. Next, the relationships between S2SIM/SF-S2SIM and the dq/sequence impedance models have been developed based on matrix transformation and the frequency shifting techniques. Finally, the electro-magnetic stability of the practical DFIG-based wind farms, associated with large-scale ac grids in China, have been well evaluated by the proposed S2SIM/SF-S2SIM based electro-magnetic stability method. [ABSTRACT FROM AUTHOR]