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It is well known that the phase stability of CsPb(I1−xBrx)3 (0 ≤ x ≤ 1) perovskite materials is enhanced under humid environments with the increase of Br− concentration in film, however, the bandgap (Eg) is also widened synchronously, resulted in limiting the light harvesting and then reducing the power conversion efficiency (PCE) of devices. Hence, how to realize the compatibility of high stability and high PCE is a challenge for device based on CsPb(I1−xBrx)3. In this work, the two- (2-T) and four-terminal (4-T) tandem solar cells (TSCs) consisting of a CsPb(I1−xBrx)3 top sub-cell and a crystalline silicon (c-Si) bottom sub-cell are constructed and compared. It is found that in the case of 2-T configuration, performance of device is very sensitive to the Eg and the thickness of top sub-cell, and a maximum PCE of 29.23% is achieved only for the CsPbI3 top sub-cell at an optimum thickness of 275 nm. However, in the 4-T formation, devices present a weak dependence on the Eg and the thickness of top sub-cell, and PCEs above 28.5% can be obtained when CsPbBr3 is used as top sub-cell. These results highly underline the application potential of 4-T CsPb(I1−xBrx)3/Si TSCs, especially for CsPbBr3/Si TSC. more...

In organic photodetectors, photomultiplication is mainly originated from interfacial and/or bulk charge traps, which induces slow response due to the slow release of trapped charges and strongly limits the optimization of the overall performance. This study has exhibited a remarkable case that the gain (>1) and response speed of the lateral photodetectors are promoted simultaneously and effectively by increasing the trap ratio. For lateral photodetectors with silver nanoparticles and PDPPBTT:PC61BM bulk heterojunction, the gain increases from 12.7 to 19.8 and the fall time decreases from 313.4 to 172.9 ms as the PC61BM ratio increases from 5:1 to 1:1. The lateral photodetector structure with a long electrode distance has been testified to play the key role for simultaneous promotion compared with vertical photodiodes, allowing the charges to trap well in the PC61BM-rich phase at a high PC61BM ratio and accumulation of multiple built-in electric fields. The long channel distance and silver nanoparticles also effectively restrain the increment of dark current with PC61BM loading, resulting in a high detectivity of 1.7 × 1012 Jones under 0.031 mW cm-2 @ 820 nm. It is of great theoretical and practical value for the high-performance photodetectors with simultaneous high photomultiplication and quick response. more...

Nowadays, purchasing the products similar to the styles of stars’ products has become a new trend in e-commerce platforms. Clothing transaction constitutes to the major part of these kinds of online purchasing. Traditional methods firstly segment clothes from human body and then input the segmented clothing image patch into a retrieval system as a query in a way that similar clothing items could be retrieved. However, the segmented clothing images usually contain complex backgrounds, and these clothing items appear to be twisted, as they are segmented from human body straightforwardly. In order to assist this cross-scenario clothing retrieval, this paper introduces a new triple-supervised GAN (TripleGAN) model by translating the clothes on human body into tiled clothes. Our model was trained on a large-scale dataset including over 30,000 clothing pairs constructed by ourselves. Extensive experimental results exhibit that our model consistently can generate tiled clothing images with more delicate details and higher quality compared with other models. Our model also shows promising performance in terms of cross-domain clothing retrieval in real-life applications. more...

Object detection in images collected by Unmanned Aerial Vehicles (UAVs) constitutes a challenging task in computer vision, due to difficulties of learning a well-trained object detection model for handling instances in UAV images with arbitrary orientations, variation in different scales, irregular shapes, etc. In order to facilitate object detection research and extend its applications in natural scenarios by using UAVs, this paper presents a large-scale benchmark dataset, MOHR, aiming at performing multi-scale object detection in UAV images with high resolution. A total of 90,014 object instances with labels and bounding boxes were annotated. In order to build a baseline for object detection on the MOHR dataset, we performed an empirical study by evaluating six state-of-the-art deep learning-based object detection models trained on our proposed dataset. Experimental results show promising detection performance, but also demonstrate that the dataset is quite challenging for adopting natural image-based object detection models for UAV images. more...

The pore size, pore structure and porosity of porous scaffold play a vital role in bone regeneration, but its optimal shape is still unclear. In this study four kinds of porous titanium alloy scaffolds with similar porosity (65%) and pore size (650µm) and different structures were prepared by selective laser melting. Four scaffolds were implanted into the distal femur of rabbits to evaluate their bone tissue growth in vivo. Micro-CT and hard tissue sections were performed 6 and 12 weeks after the operation to reveal the bone growth of the porous scaffold. The results show that diamond lattice unit (DIA) bone growth is the best in four topological scaffolds. Through computational fluid dynamics (CFD) analysis, the permeability, velocity and flow trajectory inside the scaffold structure were calculated. The internal fluid velocity difference of the DIA structure is the smallest, and the trajectory of fluid flow inside the scaffold is the longest. It is beneficial to the growth of blood vessels and the transport of nutrients, and can promote bone formation. In this study, the mechanism of bone growth in different structures was revealed by the method of in vivo experiment combined with CFD, providing a new theoretical basis for the design of bone scaffolds in the future. more...

In recent years, inorganic CsPbBr3-based perovskites have accomplished considerable progress owing to their superior stability under harsh humid environment. The power conversion efficiency (PCE) of CsPbBr3 perovskite solar cells (PSCs) has seen an unprecedented development from 5.74% to 10.91% with the improvement of the CsPbBr3 crystal quality. Despite extensive research efforts, the device efficiency of the CsPbBr3-based PSCs still lags behind that of other hybrid perovskite materials. Therefore, there is a significant interest in further boosting the performance of all-inorganic CsPbBr3 PSCs by the synergic optimization of films and device interfaces. In this review, we have discussed and summarized recent advances and methodologies related to CsPbBr3 films and PSCs. Furthermore, we discuss different fabrication strategies such as solution-based and vapor-based methods and their influence on the properties of CsPbBr3, particularly the morphology of films. Moreover, the timeline of improvement of the device efficiency from 2015 to 2020 is comprehensively addressed and developments are clearly sorted out by addressing critical factors influencing the photovoltaic performance. We further highlight state-of-the-art engineering strategies for CsPbBr3 PSCs that facilitate the crystallization control, charge extraction, suppression of charge recombination, and defect passivation in a systematic manner. At the end of the review, the summary and perspectives are presented along with beneficial guidelines for developing highly efficient and stable CsPbBr3 PSCs. more...

Generally, electrochemical energy storage devices share fundamental processes involving the diffusion and storage of ions and transport of electrons in electrode materials. Oriented 3D carbon materials can achieve better rapid ion diffusion and rapid charge conduction at the same time due to their low tortuosity and orderly conduction path. In this work, oriented microchannel carbon materials were prepared by carbonizing delignified poplar wood slices. The delignified wood-based carbon material displays massive intertubular lumina and unique aligned microchannel structure, which imparts good flexibility. This unique structure not only significantly increases the surface area of the electrode material accessible by the solid electrolyte, but also forms efficient and orderly electron conduction paths. In addition, the unique porous aligned microchannel structure also provides huge possibilities for regulating energy storage performance. The PANI nanowire array evenly covered the surface of the aligned carbon microchannel, and the unique porous aligned microchannels could be effectively retained. The DWCPA-1 interdigitated flexible solid supercapacitor exhibits significantly better electrochemical performance, cycle stability and folding endurance than that by the DWFC-800 based flexible interdigital solid supercapacitor. This indicates that the delignified wood-based flexible carbon material is an ideal basic flexible self-supporting electrode material, which has a good application potential in the field of flexible solid-state energy storage. more...

With the rapid development of near-infrared absorbing acceptor materials, the photoelectric conversion efficiency of polymer solar cells (PSCs) has been greatly improved in the past several years. However, serious charge recombination close to the cathode interlayer, like sol–gel derived zinc oxide (sg-ZnO), usually restrains the overall device performance, which is attributed to the mismatch between the relatively poor electron transport properties of the cathode interlayer and the largely increased photocurrent from the widely extended absorbing active layer. In this work, we demonstrate a novel strategy for in situ induced crystallization of zinc oxide (ic-ZnO) that shows increased crystallinity relative to the classic sg-ZnO, and such ic-ZnO is proved to reduce the interfacial charge recombination efficiently in PSCs. ic-ZnO was synthesized by a heterogeneous nucleation process, using as-synthesized zinc oxide (as-ZnO) nanoparticles as the nucleus in the precursor solution of sg-ZnO. By using this film as an efficient electron transport layer, a power conversion efficiency of 16.62% was achieved in inverted PSCs. Our results clearly indicate that increasing the crystallinity of zinc oxide by in situ induced crystallization is a facile strategy to meet the demands of high performance non-fullerene PSCs. more...

In this article, a novel simulation–optimization method is proposed for the simultaneous design of a heat-integrated coal-to-SNG/MeOH (CTSM) polygeneration process, aiming at exergy efficiency enha... more...

This paper presents new theoretical results on the multistability of switched recurrent neural networks with radial basis functions and state-dependent switching. By partitioning state space, applying Brouwer fixed-point theorem and constructing a Lyapunov function, the number of the equilibria and their locations are estimated and their stability/instability are analyzed under some reasonable assumptions on the decomposition of index set and switching threshold. It is shown that the switching threshold plays an important role in increasing the number of stable equilibria and different multistability results can be obtained under different ranges of switching threshold. The results suggest that switched recurrent neural networks would be superior to conventional ones in terms of increased storage capacity when used as associative memories. Two examples are discussed in detail to substantiate the effectiveness of the theoretical analysis. more...

The geometry of porous bone scaffolds has an important effect on its bone ingrowth, but there is still a lack of in-depth research on this aspect. This study establishes a curved structure and a strut structure with a porosity of 65% and a pore size of 650 μm. The rabbit femoral condyle implants were used to assess the bone ingrowth. The pressure cloud chart and the velocity streamline inside the scaffold structure were calculated by computational fluid dynamics (CFD). The results show that the osteogenic property of a curved structure is better than that of a strut structure, but the mechanical property is not as good as that of the strut structure. The velocity streamline and velocity difference inside the scaffold structure has a great influence on bone ingrowth. Under the same condition, the smaller the fluid velocity difference inside the scaffold structure, the larger the fluid flow area, and the better the bone tissue growth. Studies have shown that the geometry of the bone scaffold can be optimized according to different implantation sites to meet the requirements of different implantation sites. more...

Efficient and selective heavy atom-free singlet oxygen photosensitizers (HAFPS) are highly desirable for chemistry, pharmaceutical sciences, phototherapy, and environmental sciences. The donor–acce... more...

With the increasing popularity of online shopping, searching for products with images for item retrieval has gradually become an effective approach. This trend is especially evident in the fashion industry. In common media, clothing items are usually worn on the human body. They can be straightforwardly segmented from the source media by utilizing detection or parsing algorithms. However, this may be deleterious to retrieval performance due to distortion, occlusion, and different backgrounds. In this article, a stepwise translation framework using generative adversarial network and thin plate spline is developed to transfer human body images to tiled clothing images, which can be directly used for clothing retrieval. Experimental results demonstrate the effectiveness of the resultant tiled images produced from our framework in comparison to other extant methods. more...

Recently, inorganic perovskite solar cells (PSCs) based on CsPbBr3 have triggered incredible interest due to the demonstrated excellent stability against thermal and high humidity environmental conditions. However, the power conversion efficiency (PCE) of the CsPbBr3-based PSCs is still lower than that of the organic-inorganic hybrid one, because of the large band gap and serious charge recombination at the interface or inside the device. Here, the working mechanism of the devices with normal n-i-p planar structure is modeled and investigated using SCAPS 1D simulation software. The simulation results state that the proper band structure of PSCs is crucial to carrier separation and transport. The high interface recombination, originated from the large band offsets of the electron transport material (ETM)/absorber and absorber/hole transport material (HTM) respectively, can be effectively diminished with the continuous gradient junction design of the absorber, and a PCE of 11.58% is obtained with a high open-circuit voltage (VOC) of 1.68 V. Moreover, by building a heterojunction bilayer absorption scenario of CsPbIBr2/CsPbBr3 and employing ZnOS and Cu2ZnSnS4 films as the ETM and HTM respectively, the PCE of PSCs is further increased to 15.89%, caused mainly by the enhancement in short-current density (JSC). Moreover, reducing the interface defect density is also very important to improve the performance of PSCs. These results will provide theoretical guidance for improving the performance of the CsPbBr3-based PSCs. more...

Heat exchanger network (HEN) plays an important role in chemical process industry owing to its significant effect in energy recovery. Compression–absorption cascade refrigeration system (CACRS) is ... more...

A multiobjective optimization (MOO) framework considering the dual objectives of the economy and the environment is presented in this work for the extended integration of interplant heat exchanger ... more...

This paper is concerned with the pinning synchronization control issue for a class of discrete-time complex dynamical networks. By resorting to the interval observer approach, a novel pinning synchronization control strategy is adopted to control a small fraction of the network nodes with hope to reduce the implementation cost. By using the Lyapunov stability theorem, some synchronization criteria have been derived to ensure the desired synchronization performance. Finally, a numerical simulation is presented to illustrate the effectiveness and usefulness of the theoretical results. more...

Rotating ultrasonic vibration assisted EDM is a composite machining method that uses EDM to etch a metal surface and adds rotating and ultrasonic vibration. It has high efficiency and a wide range of workpiece materials. Aiming at the structural characteristics of rotary ultrasonic vibration assisted EDM machine tool, the errors caused by the main moving parts of the machine tool were analyzed. The structure relationship is described by multi-body system theory, and the geometric error model is deduced by homogeneous coordinate transformation method. The aim was to improve the overall accuracy, reduce the cost, trace the error source, and get the corresponding relationship between the basic geometric errors and the precision parameters of the related parts. Under the requirement of ensuring the overall accuracy, an optimization function was established that minimizes the cost and relaxes all accuracy parameters to the greatest extent. Finally, MATLAB and its genetic algorithm toolbox was used for analysis. Verification shows that this model can properly reduce the cost on the premise of ensuring the accuracy. more...

The optimal work and heat integration for pressure and temperature manipulation has been brought into sharp focus due to its paramount significance in reaching considerable energy and expenditure savings. This article proposes an upgraded stage-wise superstructure that simultaneously performs heat integration among unclassified hot/cold streams and direct work integration between pre-classified high/low-pressure streams. An efficiently innovative optimization model for the cost-effective synthesis of direct work and heat exchanger networks (WHENs) is established. A key strategy is to implement the identification of stream types (hot/cold). To this end, an improved superstructure-based model is presented for heat exchanger networks synthesis, combined with an optimized selection of multiple pressure-manipulation units in each stage of the WHEN superstructure. Besides, the proposed method can surpass certain limitations in previous studies that the coupling of direct work integration and heat integration is not considered. Our approach can effectively design preferable WHEN configurations and offer an alternative for enhancing thermal and mechanical energy recovery at the lowest total annual cost. Two case studies are conducted to assess the effectiveness of our proposed methodology, in which the better configurations can be obtained with considerable cost savings of 39.2% and 6.8% when compared to the corresponding literature solutions, respectively. more...

There is a large gap between the elastic modulus of the existing femoral stem and the host bone. This gap can lead to long-term complications, such as aseptic loosening and, eventually, a need for revision surgery. The porous metallic biomimetic femoral stem can effectively reduce stress shielding and provide firm implant fixation through bone ingrowth. The purpose of this research is to investigate the application of different porous femoral stems in relieving bone resorption and promoting osseointegration by finite element analysis. We present an intuitive visualization method based on a diamond lattice structure to understand the relationship between pore size, porosity, bone ingrowth criteria and additive manufacturing constraints. We further obtain an admissible design space of diamond lattice structure for porosity selection. We evaluate the relative micromotion of bone-implant interface and bone volume with density loss for three femoral stems with diamond lattice-based homogenous porous structures in admissible design space. We also evaluate porous femoral stems with four different grading orientations along the axial and radial directions of the femoral stem. These include an axial graded femoral stem with a porosity increased distally (DAGS), an axial graded femoral stem with a porosity increased proximally (PAGS), a radial graded femoral stem with a porosity increased inwardly (IRGS), and a radial graded femoral stem with a porosity increased externally (ERGS). The results indicate that: (i) homogenous porous femoral stems with 40% porosity, (ii) DAGS and (iii) IRGS can maintain the relative micromotion of the bone-implant interface in the safety range for bone ingrowth. The calculated volumes of bone with density loss in the cases of DAGS and IRGS are 3.6% and 3.3%, respectively, which are nearly 74% lower than that of fully dense stems. Therefore, DAGS and IRGS have an evident advantage in promoting osseointegration and relieving bone resorption. Thus, the graded femoral stem is more promising than the homogeneous porous stem. more...

As a success-oriented system reliability and safety-analysis technique, the GO methodology has been applied in a variety of real-world safety-critical industrial fields. Common-cause failure (CCF) is the simultaneous failure of multicomponents within a system due to the same root cause. An enhancement approach for the original GO methodology is proposed in this paper to support CCF modeling and calculation both in graphical modeling aspect and algorithm aspect. First, a new concise and formalized GO operator (named CCO) is introduced to represent complicated CCF event, which makes the CCF modeling process intuitive and concise for analysts. In algorithm aspect, the mapping rule is given and demonstrated to transform new CCO operator with impacted multiple operators to the corresponding Bayesian network (BN) fragment. Second, general mapping programmable process is presented on transforming any CCF enhanced GO model to the corresponding BN. Furthermore, using BN's inference capability, the enhanced GO model with CCF can be calculated efficiently. Nevertheless, the diagnosis process can be performed to investigate the weak points of the modeled system. Finally, a case study is performed to demonstrate the modeling process by means of CCF enhanced GO model. The calculation result shows that CCF has significant influence on the system reliability. Using diagnosis analysis, the CCF event can be confirmed as the major cause leading to system failure. more...

This paper is concerned with the interval observer-based control for a class of nonlinear systems with unknown nonlinearities. For the purpose of effectively reducing network congestion and improvi... more...

To design novel conjugated polymers and improve interfacial interaction with semiconductor is one of directions to develop high-efficient photocatalysts with harvesting photons and boosting catalytic activities. Herein, two novel linear conjugated polymers poly[(thiophene-ethylene-thiophene)-thiophene] (PTET-T) and poly[(thiophene-ethylene-thiophene)-thiophene-3-carboxylic acid] (PTET-T-COOH) were successfully synthesized by a simple Stille coupling reaction. Their heterojunction with TiO2, i.e, PTET-T/TiO2 (C1) and PTET-T-COOH/TiO2 (C2), exhibited outstanding photocatalytic activity for degrading Rhodamine B, methylene blue and tetracycline. The energetic “lock-in effect” between PTET-T-COOH and TiO2 through carboxyl groups and hydroxyl groups interaction has been proved to greatly improve the interface charge transfer ability and suppress the electron-hole recombination in PTET-T-COOH/TiO2. Thus, by regulating the dosage of polymers, the 15% PTET-T-COOH/TiO2 showed the optimized photocatalytic activity with excellent chemical stability, and its kinetic rate constant was determined to be 41.7 times of that of TiO2. This work provided a new effective strategy of designed and explored organic semiconductor-inorganic heterojunction photocatalysts with broaden absorption, repeatability and high-charge mobility. more...

With the popularity and development of the Internet, purchasing items that are similar to those that appear in videos or on fashion websites has gradually become an established trend in online commerce. Currently, determining how to accurately locate these similar items in a huge e-commerce database poses a major challenge. When processing images that contain clothes worn on the human body, traditional methods usually detect the clothes in these images first, add them to a database for clothing retrieval, and finally identify a few pieces of clothing with a high degree of similarity for recommendation. Generative adversarial networks (GANs) have been widely and successfully utilized in the field of image-to-image translation. In this paper, GAN is used to transfer human body images into tiled clothing images, which can be directly used for clothing retrieval. To achieve this, a category-supervised GAN under a cascading structure is proposed. For model training, a large-scale dataset was compiled that contains 39,521 image pairs. Experimental results demonstrate that the tiled clothing images generated by our proposed method deliver higher quality, as well as performance superiority, for clothing retrieval in comparison to other existing methods. more...

Intermedium agents play an important role in indirect interplant heat integration. Each of them has a unique performance in heat recovery, however seldom conjunctively employed, which simplifies th... more...

Solvents have been widely used in process manufacturing industries. When involved in liquid-phase organic synthesis reactions, solvents can reduce the activation energy of reactions between the reactants and the transition state through solvation effects. However, undesirable side reactions can also be performed between solvents and the reaction system (the reactants and products), which should be avoided for producing unnecessary byproducts in the reaction system. In this paper, an optimization-based methodology is proposed for inert reaction solvent design. In this method, first, a Group Contribution (GC)-based reaction thermodynamic model is developed to quantitatively identify the thermodynamic feasibility of side reactions between solvents and the reaction system. Then, the SMARTS (SMiles Arbitrary Target Specification)-based reaction generation algorithm is employed to generate possible side reactions between solvents and the reaction system, helping to integrate the developed GC-based reaction thermodynamic model with the Computer-Aided Molecular Design (CAMD) problem for designing inert reaction solvents through the formulation and solution of the Mixed-Integer Non-Linear Programming (MINLP) model. Due to the nonlinear equations in the MINLP model, a decomposition-based solution strategy is employed to solve the optimization problem. Finally, two case studies are presented to demonstrate the feasibility and effectiveness of the proposed optimization-based methodology for promising inert reaction solvent design. more...

The traditional hydrolysis/hydrothermal two-step preparation method of carbon/inorganic nanohybrid material usually exhibit the disadvantage of aggregation and precipitation. Therefore, the above method has certain difficulty in the synergistically regulation of the aggregation morphology and microscopic morphology of carbon/inorganic nanohybrid materials. In this paper, cellulose nanofiber and chitin nanofiber are used as the carrier material of inorganic nanomaterials, which can maintain the uniform and stable dispersed state during the hydrolysis of metal ions and hydrothermal treatment. The uniform inorganic nanoparticles uniformly distributed in the randomly stacked nanosheets even if the total content of metal ions increases to 6 mmol. The natural nanofibers/NiFe2O4 nanoparticles composite nanosheets with adjustable stacked pore structure can be prepared from natural nanofibers/NiFe2O4 nanoparticles composite hydrogel via unidirectional freeze-shaping. The carbonization temperature and carbonization time are more effective in synergistically regulation of the stacked porous nitrogen-doped carbon/NiFe2O4 nanohybrid nanosheets. Extending carbonization time or increasing carbonization temperature not only allows the growth of inorganic nanomaterials, but also causes damage to the nanosheets (such as broken pore and the small, wrinkled morphology of the nanohybrid nanosheets). NC/NiFe2O4-1.5/700/3 exhibits the highest gravimetric capacitance (up to 458 F g−1 at a constant current density of 0.5 A g−1). more...

Multilayer tetrahedral amorphous carbon (ta-C) films comprising alternating layers of different sp3 contents have been fabricated by periodically adjusting the bias voltage of filtered cathodic vacuum arc (FCVA) system. The microstructure, tribological and corrosion behaviors of the multilayer ta-C films deposited on YG6 cemented carbide were systematically investigated. Results showed that the multilayer structure effectively reduced the residual stress and restrained spalling of ta-C film, which frequently occurred in single-layer structure. The hardness and Young's modulus of multilayer ta-C films decreased with diminishing sp3 content of soft sublayer. Compared to the YG6 substrate, multilayer ta-C films exhibited much lower friction coefficient between 0.06 and 0.08 and effectively reduced the wear rate. Multilayer ta-C film deposited at bias voltage alternating between −50 V and –150 V (M-1 film) had the lowest friction coefficient of 0.06 and the lowest wear rate of 2.87 × 10−7 mm3/N m. The difference in anti-wear performance among the multilayer ta-C films was associated with the ratio of hardness to elastic modulus (H/E ratio). The electrochemical corrosion test confirmed the effective corrosion protection provided by the multilayer ta-C films, and the M-1 film obtained the highest polarization resistance. Judging from electrochemical impedance tests, the existence of some extent of microdefects could be the main factor limiting the electrochemical corrosion performance of the multilayer ta-C films. more...

Triethylene glycol (TEG) is widely applied to the removal of water in shale gas. This study presents a framework of economic evaluation and environmental assessment for two TEG-based dehydration approaches, namely, conventional dehydration process and stripping gas dehydration process. The latter one features a higher solvent concentration, at the expense of extra shale gas loss. On the basis of process simulation, the effects of theoretical stage and solvent concentration on economic and environmental performances are investigated for process optimization. A hybrid life cycle inventory (LCI) model that consists of input-output and process-based methods is developed to evaluate the environmental impacts associated with shale gas dehydration. The results show that utility consumption and shale gas loss are dominant sources for the emissions of CO2 and NOx, while soot is mainly derived from embodied emissions. Based on the tradeoff between the total annual cost and environmental impacts, the optimal case with superior economic and environmental performances is acquired. Ultimately, sensitivity analyses are conducted for systematic comparison of two approaches under different compositions of raw shale gas and specifications of water removal. more...

A perylene bisimide functionalized with four 4-carboxyphenoxy substituents at bay area (PBI-COOH) was embedded in sol-gel-derived zinc oxide (ZnO) to fabricate organic-inorganic hybrid photoconductive cathode interlayers (ZnO:PBI-COOH) that can be annealed at a rather low temperature of 120-130 °C as desired for plastic substrates for flexible devices. For these interlayers, the structural defects including oxygen vacancy and residual hydroxy groups are reduced that leads to increased electron mobility, and a photoinduced electron transfer from the organic dopant into the conduction band of ZnO endows the hybrid thin film with relatively higher conductivity when compared to the undoped ZnO thin film. The low-temperature-processed hybrid thin films were applied on indium tin oxide electrodes to produce inverted organic solar cells (OSCs) with power conversion efficiencies of 11.68 and 13.48% when using J71:ITIC and PBDB-T-2Cl:IT4F as active layers, respectively. Finally, flexible OSCs are fabricated on poly(ethylene terephthalate) substrates that maintained stability with relatively high performance after 100 times bending. more...

Polymers are widely used to manufacture many chemical products. Often, polymers are designed by trial-and-error, which is expensive and time-consuming. In this work, a new optimization-based comput... more...

Process systems engineering research focuses on the planning, design, operation, and safety of process systems rather than unit operations. In response to the rapid growth of the chemical process industry in the last 20 years in China, advanced system integration and process safety technologies are investigated and applied for better resource utilization, less environmental impact, and safer working places. In this regard, the review in this article consists of four main achievements: (1) process synthesis, (2) energy system integration, (3) water system integration, and (4) process safety management. The purpose of process synthesis and integration is to improve resource and energy utilization, at the same time lowering by-products and emissions. Optimization is conducted on process structure and operation, following the principles of resource coupling and energy cascade utilization. Typical examples are coupling of coal and hydrogen-rich resources and integration of coal-based polygeneration process of chemicals, electricity, and heat. Energy integration implements the coordinated optimization of total site energy systems. Reviews are made on specific methodologies based on the thermodynamics and applications of design and retrofit in ethylene, oil refining, and synthetic ammonia industries. There are energy savings by 10%–20% and yields increasing by 20%–30%. In addition, waste heat recovery and cold energy utilization are also important research areas. Reviews on the progress of water system integration and its industrial applications are also conducted. It includes the direct reuse, regeneration, and reuse/recycle in water systems and systems with internal water mains. Finally, safety management and technologies are also indispensable technological advancements of the process. The legislation system and the work safety-related standard system have been gradually established and enforced. Process safety research progress is reviewed, and questions are proposed for improving the accident prevention and safety management agenda. more...

This paper is concerned with the multistability of switched neural networks with piecewise linear activation functions under state-dependent switching. Under some reasonable assumptions on the switching threshold and activation functions, by using the state-space decomposition method, contraction mapping theorem, and strictly diagonally dominant matrix theory, we can characterize the number of equilibria as well as analyze the stability/instability of the equilibria. More interesting, we can find that the switching threshold plays an important role for stable equilibria in the unsaturation regions of activation functions, and the number of stable equilibria of an $n$ -neuron switched neural network with state-dependent parameters increases to $3^{n}$ from $2^{n}$ in the conventional one. Furthermore, for two-neuron switched neural networks, the precise attraction basin of each stable equilibrium point can be figured out, and its boundary is composed of the stable manifolds of unstable equilibrium points and the switching lines. Two simulation examples are discussed in detail to substantiate the effectiveness of the theoretical analysis. more...

Solvents have been widely used in chemical manufacturing processes. When involved in liquid homogeneous-phase kinetic reactions, they can have significant impacts on the reaction product yield. In this paper, an optimization-based framework is developed for reaction solvent design. The framework first identifies a reaction kinetic model using a hybrid method consisting of three steps. In step one, a rigorous thermodynamic derivation based on CTST (Conventional Transition State Theory) is performed to formulate a primary reaction kinetic model. In step two, a knowledge-based method is used to select additional solvent properties as supplementary descriptors to account for quantitative correction to the model and thereby improving the prediction accuracy. In step three, model identification is performed to obtain the best regressed reaction kinetic model. This hybrid modelling method is tested through two case studies, namely Diels-Alder and Menschutkin reactions, and an impressive consistency of the results is observed when the infinite dilution activity coefficients (calculated by COSMO-SAC model), hydrogen-bond donor, hydrogen-bond acceptor and solvent surface tension are selected as descriptors in the final reaction kinetic model. The GC-COSMO and GC (Group Contribution) methods are combined for the prediction of these descriptors. Finally, the Computer-Aided Molecular Design (CAMD) technique is integrated with the derived kinetic model for reaction solvent design by formulating and solving a Mixed-Integer Non-Linear Programming (MINLP) model. A decomposition-based solution algorithm is employed to manage the complexity involved with the nonlinear COSMO-SAC equations. Promising reaction solvents are identified and compared with those reported by others, indicating wide applicability and high accuracy of the developed optimization-based framework. more...

Over the last three decades, flexibility and controllability considerations for heat exchanger networks (HENs) have received great attention, respectively. However, they should be simultaneously incorporated in HEN synthesis to allow the economic performance to be achievable in a practical operating environment. This paper proposes a method for simultaneous synthesis of flexible and controllable HEN by considering their coupling. The key idea is to add the bypasses with optimized initial fractions and positions to explore such coupling, and consequently enabling HENs to be operated successfully over a range of disturbance variations. These are implemented by identifying and quantifying disturbance propagations, and then examining the sensitivity of bypasses to the entire HEN. In this way, the superstructure-based mixed integer non-linear programming (MINLP) with objective function of minimizing the total annual cost is formulated. A case study is used to demonstrate the application of the proposed method. Quantitative measures and dynamic simulation show the ability to provide the satisfactory flexibility and controllability of the obtained HEN. more...

This paper presents a flexible heat exchanger network (HEN) synthesis methodology to cope with (i) the fluctuations of uncertain process parameters and (ii) the gradually accumulated deposit, which... more...

Chemical product design determines the structure and constitution of products that satisfies all desired properties and functions. Molecular products are usually employed as the main active ingredient, or manipulated to obtain a specific function for chemical-based products, while mixtures are one of the most widely used chemical products. Therefore, the design of molecular and mixture products is the foundation of all chemical product design problems. In this paper, the development of an optimization-based framework for molecular and mixture product design is presented. The design work-flow consists of three steps involving preliminary design, CAMD (Computer Aided Molecular-Mixture Design), as well as product evaluation and verification. In the preliminary design step, the product attributes are collected and converted into a set of desired physico-chemical properties with associated targets to formulate the CAMD problem. In the CAMD step, an optimization-based mathematical programming model is established and solved to generate feasible molecules and/or mixtures together with optimal product candidates. In the product evaluation and verification step, final selection of the optimal chemical product is made based on evaluation of in-use product performance attributes and additional properties not included in the CAMD step. The three steps have been implemented within a molecular-mixture design toolbox called “OptCAMD”, which is integrated in ProCAPD, a versatile tool for chemical product design and evaluation. Case studies highlighting different aspects of OptCAMD involving the design of various types of chemical products are presented. more...

Dressing in clothes based on the matching rules of color, texture, shape, etc., can have a major impact on perception, including making people appear taller or thinner, as well as exhibiting personal style. Unlike the extant fashion mining literature, in which style is usually classified according to similarity, this paper investigates clothing match rules based on semantic attributes according to the generative adversarial network (GAN) model. Specifically, we propose an Attribute-GAN to generate clothing-match pairs automatically. The core of Attribute-GAN constitutes training a generator, supervised by an adversarial trained collocation discriminator and attribute discriminator. To implement the Attributed-GAN, we built a large-scale outfit dataset by ourselves and annotated clothing attributes manually. Extensive experimental results confirm the effectiveness of our proposed method in comparison to several state-of-the-art methods. more...

Superhard CrB2 coatings with hardness around 45.7 ± 1.6 GPa were deposited on cemented carbide substrates via a direct current magnetron sputtering at the deposition temperature of 300 °C. The composition, microstructure and corrosion resistance of the deposited coatings were investigated. The results revealed that the deposited CrB2 coating had a preferred (0 0 1) orientation and dense nanocolumnar structure. The great improvement in corrosion resistance of CrB2 coated substrate was obviously observed from potentiodynamic polarization and electrochemical impedance spectroscopy. The formation of Cr2O3 was supposed to be the key factor for the obvious passivation phenomenon. Consequently, the corrosion current density was reduced by 100-fold in combination with a higher polarization resistance compared with the pristine substrate. more...

Work integration is a significantly promising strategy to achieve notable reduction in energy consumption. Work recovery has been performed by graphical integrating method and transhipment model in open literatures, but the economic performance is ignored. To overcome the limitations, this paper proposes an extended superstructure-based optimization model for simultaneous synthesis of direct work exchanger networks (WEN), which aims at the optimal trade-off between capital investment and operational expenditure. The operational expense involves electricity generated by expanders and electricity consumed by compressors. The developed stage-wise superstructure, which is different from that of heat exchanger networks (HEN), should consider utility compressors/expanders as well as valves in parallel at each stage of the superstructure, and utility compressors in series for low-pressure streams prior to entering the superstructure. The direct WEN superstructure is formulated as a mixed-integer nonlinear programming (MINLP) model with the objective of minimizing total annual cost (TAC). Three example studies are conducted to assess the efficacy of the proposed model. The results indicate better direct WEN configurations can be obtained with considerable savings in TAC, in which the minimum pressure difference sensitivity study is conducted to further confirm the effectiveness and importance for the effect of pressure manipulation on output. more...

Urban renewal is an ideal approach to promoting the value of the urban fabric and improving the sustainability of the urban environment. This study, which shows the continuity of research on sustainable urban renewal, aimed to identify sustainable urban renewal literature based on a library analysis of scientific research since 2000. A total of 3971 scientific papers from the SCIE (Science Citation Index Expanded) and SSCI (Social Sciences Citation Index) databases were reviewed to examine how research concerning “sustainable urban renewal” has emerged and developed in the past 20 years. The h-indices and impact factors of the most relevant journals in urban renewal and sustainable development since 2000 were analyzed. The most frequently cited articles were analyzed using analysis of social networks (VOSviewer). The results revealed potential future focuses of research and guidelines that link urban renewal and sustainability: the engagement of all stakeholders in the decision-making process, the involvement of residents in projects, the development of cooperation between towns and cities, the preservation and reuse of built and industrial heritage while respecting environmental law, and, finally, the search for new financing techniques. These potential future research topics were analyzed in four research areas so that sustainable development can easily be integrated into an urban renewal project. more...

In the present study, we upgraded Pyrococcus furiosus Argonaute (PfAgo) mediated nucleic acid detection method and established a highly sensitive and accurate molecular diagnosis platform for the large-scale screening of COVID-19 infection. Briefly, RT-PCR was performed with the viral RNA extracted from nasopharyngeal or oropharyngeal swabs as template to amplify conserved regions in the viral genome. Next, PfAgo, guide DNAs and molecular beacons in appropriate buffer were added to the PCR products, followed by incubating at 95 °C for 20–30 min. Subsequently, the fluorescence signal was detected. This method was named as SARS-CoV-2 PAND. The whole procedure is accomplished in approximately an hour with the using time of the Real-time fluorescence quantitative PCR instrument shortened from >1 h to only 3–5 min per batch in comparison with RT-qPCR, hence the shortage of the expensive Real-time PCR instrument is alleviated. Moreover, this platform was also applied to identify SARS-CoV-2 D614G mutant due to its single-nucleotide specificity. The diagnostic results of clinic samples with SARS-CoV-2 PAND displayed 100% consistence with RT-qPCR test., Graphical abstract Image 1 more...

The outbreak of COVID-19 caused a worldwide public health crisis. Large-scale population screening is an effective means to control the spread of COVID-19. Reverse transcription-polymerase chain reaction (RT-qPCR) and serology assays are the most available techniques for SARS-CoV-2 detection; however, they suffer from either less sensitivity and accuracy or low instrument accessibility for screening. To balance the sensitivity, specificity, and test availability, here, we developed enhanced colorimetry, which is termed as a magnetic pull-down-assisted colorimetric method based on the CRISPR/Cas12a system (M-CDC), for SARS-CoV-2 detection. By this method, SARS-CoV-2 RNA from synthetic sequences and cultured viruses can be detected by the naked eye based on gold nanoparticle (AuNP) probes, with a detection limit of 50 RNA copies per reaction. With CRISPR/Cas12a-assisted detection, SARS-CoV-2 can be specifically distinguished from other closely related viruses. M-CDC was further used to analyze 41 clinical samples, whose performance was 95.12%, consistent with that of an approved Clinical RT-qPCR Diagnosis kit. The developed M-CDC method is not dependent on sophisticated instruments, which makes it potentially valuable to be applied for SARS-CoV-2 screening under poor conditions. more...

To eliminate voltage violations and improve the security and economy of wind farms, model-based volt/var optimization has been widely but heavily relies on accurate wind farm models. However, numerous wind farms lack of well maintained models because of rapid construction, limited operation staff and changing environment. It motivates us to develop a data-driven wind farm volt/var control based on deep reinforcement learning (DRL). In order to improve the stability, efficiency and optimality of existing DRL-based methods, entropy-regulation technique is utilized. Numerical simulations not only demonstrate the effectiveness of such data-driven volt/var control method, but also show the superiority of our proposed method. more...

Perovskite-type was synthesized by two methods, the combustion method and conventional solid state reaction (SSR) method. The effect of synthesis methods on sinterability and physical properties of the ceramic were investigated. The results show that there are advantages of the combustion method in producing doped lanthanum chromites. Compared with the SSR method, the combustion method reduces the sintering temperature of La0.8Ca0.2CrO3, elevates the electronic conductivity and thermal expansion coefficient (TEC) of the ceramic, due to optimizing the microstructure. At the same densities level (&ndash, 93%), the specimen synthesized by the combustion method reaches a superior electrical conductivity of 31.6 S&middot, cm-1 and a compatible TEC of 10.7 &times, 10&minus, 6 K&minus, 1 at 800 &deg, C. more...

Restricted by the energy gap rule, near-infrared (NIR) luminescent materials face great challenges. Here, we report a newly designed and synthesized organic molecule, 5,5′-([1,2,5]thiadiazolo[3,4-c... more...

Large area MoS2/Si heterojunction-based solar cell was prepared in which MoS2 thin film was directly grown on p-Si wafer using sol-gel method. Chemical bonding and microstructure analysis show that the MoS2 film was in the initial region of transition from amorphous to microcrystalline phase. Compared with the ITO/p-Si/Ag structure without MoS2, the open-circuit voltage (VOC), short-circuit current density (JSC) and fill factor (FF) of the ITO/MoS2/p-Si/Ag solar cell were improved dramatically, and the conversion efficiency (CE) increased from 1.1% to 4.6%. The insertion of MoS2 film reduced the interface defects concentration and increased the depletion region width of the solar cell, showing its enhancement effect on both chemical passivation and field passivation. more...

Diamond-like carbon (DLC) films with weak carbide metal Al and carbide metal Ti co-doping (Al/Ti-DLC) were prepared by a hybrid ion beam deposition system. The atomic ratios of doped Al to Ti were tailored via designing the special Al/Ti combined sputtering target. The composition, microstructure, roughness, residual stress, hardness, toughness, and tribological behaviors of the deposited films were systematically evaluated to explore the dependence of structural properties on Al/Ti ratios. Results indicated that the high-throughput preparation of DLC films with different Al/Ti atomic ratios was achieved by tailoring the sputtering target and process parameters without the difference in both the film thickness and total Al/Ti content. With the Al/Ti ratios in the films decreased from 8.8 to 3.0, the residual stress, hardness, and toughness of Al/Ti-DLC films increased obviously, originating from the increased fraction of titanium carbide and the reduced Al content. However, the coefficient of friction and wear rate with decreasing the Al/Ti ratio were obviously improved, which was related with the transformation of underlying friction mechanism from the sliding interface graphitization to dangling bond-passivation. The present results not only suggest a high-throughput method to fabricate co-doped DLC films, but also promote the scientific understanding and engineering application of DLC films with high performance. more...

This paper proposes an offline and runtime combined framework for the autonomous motion of snake robots. With the dynamic feedback of its state during runtime, the robot utilizes the linear regression to update its control parameters for better performance and thus adaptively reacts to the environment. To reduce interference from infeasible samples and improve efficiency, the data set for runtime training is chosen from one in several clusters categorized from samples collected in offline practice. Moreover, only the most sensitive control parameter is updated at one iteration for better robustness and efficiency. The effectiveness and efficiency of our approach are evaluated by a set of case studies of pole climbing. Experimental results demonstrate that with the proposed framework, the snake robot can adapt its locomotion gait to poles with different unknown diameters. more...

Organic phototransistors (OPTs) simultaneously introduce photo-induced holes and electrons into the structure of organic field-effect transistors (OFETs). The memory effect of the minority carrier is the origin of the large dark current and slow response during the light on/off switching, which is detrimental to the OPT performance and cycling stability. In this research, we report a novel OPT working mode by photoelectric dual control. After each light switch, the dark current is erased by the gate voltage in depletion mode which remains unchanged during light off; the photocurrent increases by device converting to accumulation mode when the light is on. In this way, high performance OPTs have been obtained in an FBT-Th4(1,4) : PC61BM (5 : 1) composite film with the structure of Si/SiO2/OTS/FBT-Th4(1,4) : PC61BM/Au electrodes, which shows a broad spectral response (maximum values at zero gate bias: R 1.2 × 105 A W−1, gain 3.7 × 105 and D* 3.18 × 1016 Jones) from 410 to 740 nm (calculated from the transfer curve). The best performance with photoelectric dual control under 0.0031 mW cm−2@405 nm is achieved with an on/off current ratio of 1.0 × 106, response 1.6 × 104 A W−1, gain 5.0 × 104, spectral detectivity 2.3 × 1017 Jones and response time sub-40 ms, which makes the phototransistor a very promising component for light sensing applications. more...