Matching Theory Research Articles

Individually frequency and amplitude tunable metamaterial absorber with sensing functions based on strontium titanate and graphene

A terahertz metamaterial absorber with sensing function based on strontium titanate (STO) and graphene is designed. The optical characteristics of the designed structures are simulated and numerically calculated by the finite difference time domain (FDTD) and coupled mode theory (CMT) method. The results show that the temperature of STO is 300 K and Fermi level of graphene is 1.0 eV, the absorptance achieves 99.8 % and 92.7 % at 0.36 THz and 2.18 THz, respectively. When the temperature of the STO is set from 250 K to 400 K, the center frequency is moved from 0.32 THz and 1.96 THz to 0.43 THz and 2.54 THz. When the temperature is stable at 300 K, the dual narrow band absorption can be converted to single narrow band absorption by tuning the Fermi level from 1.0 eV to 0 eV. The physical mechanism of the dual narrow band absorptions and active tuning is analyzed by electric field distribution and impedance matching theory. The effect of polarization direction and incident angle on the absorber performance is also investigated. In addition, we also investigated the sensing characteristics of the absorber when the Fermi level of graphene is 0 eV, and the sensitivity and figure of meritis of the structure for detecting different refractive indices is 50 GHz/RIU and 0.33/RIU. The proposed structure provides new ideas for future multifunctional terahertz device design.

Design of coupling system for Cassegrain antenna array

An optical fiber coupling system consisting of a plano-convex lens array and a coupling lens array is designed for a Cassegrain antenna array. The vector theory of reflection and refraction is used to simulate the three-dimensional ray tracing of the optical system and the spot diagrams are used to analyze optical system aberrations. The mode field matching theory is used to analyze the coupling efficiency of the optical system. The simulation results show that the central coupling system for 1550 nm has the maximum coupling efficiency of 70.92%, and the average coupling efficiency of the seven sets of coupling systems is 70.89%. This paper will provide engineers or designers with a design method of the coupling system for the antenna array.

Peer effects of working capital management: Considering the moderating effect of knowledge flow.

An important form of human learning and cognition is imitation. In environments where uncertainty is more incremental, imitation of peers is a natural response to uncertainty. While there are substantial literature documenting peer effects in other settings, the study of peer effects in working capital management is novel; little research exists on peer effects in working capital management and their impact mechanism. Using data of China's listed firms from 2010 to 2021, we empirically demonstrate significant peer effects due to working capital management. Firstly, we find that the behavior of working capital management of firms in the same industry is positively related to a firm's working capital management. We used peer firms' target debt ratio as an instrumental variable to address potential endogeneity problem. Secondly, the moderating effects test shows that the positive relationship between the behavior of working capital management of firms in the same industry and a firm's working capital management behavior is moderated by knowledge flow. Meanwhile, the peer effects in the high group of knowledge flow are greater than that of in the low group of knowledge flow. The study is based on the Active Intermodal Matching theory of psychology. It enriches the research findings on the moderating effect of peer effects and has important implications for policymaking to stimulate the economy.

Coupled single-port method based voltage stability assessment with inverter-based generators

With the increase of inverter-based generators in the power system, the proportion of traditional generators is decreasing, and their voltage support ability to the power system is weakening, the power system operation is approaching to its voltage stability limit. It is of great significance to study on-line analysis of power system voltage stability under different control manners of inverter-based generators. Firstly, impedance matching theory and coupled single-port circuit theory are introduced. Secondly, coupled single-port method based voltage stability assessment method with inverter-based generators is proposed. Then, use the impedance matching condition and proposed method to analyze the influence of inverter-based generators on voltage stability in different control manners. The proposed method can reveal the voltage stability margin of power system with inverter-based generators in the current running state, and is suitable as an on-line voltage stability approach to evaluate the proximity of voltage collapse in real time. The various scenario simulations experiment validate the effectiveness and accuracy of the proposed method. Meanwhile, experimental analysis results show that different control manners of inverter-based generators not only affect voltage stability margin but also change the weakest bus of power system.

Ultra-Wideband Polarization Insensitive Angle Filter Based on ENZ Characteristics and Dynamic Antireflection Structures

Bandwidth expansion has always been an important dimension in investigating angle filters (AFs) and is critical for optical communication and radar detection. In this paper, the AF with strong selectivity is realized by using the epsilon-near-zero (ENZ) jump characteristic of YaBa2Cu3O7 material. At the same time, for both the TE and the TM waves in the range of 237~1000 THz, the transmissivity of the AF is stronger than 0.9 by using dynamic antireflection structures (AFSs). The transfer matrix method is suitable for theoretical calculation, and the impedance matching theory is introduced to analyze the features of the AF. The increment of the thickness of superconductor material can effectively enhance the selectivity of the AF structure, and the consequence is the attenuation of transmission performances. If the temperature is covered from 0 K to 85 K, the filtering performance higher than 0.9 can still be maintained for two polarization waves. For these explicit performances, the proposed design may provide a new idea for widening the frequency bandwidth of the AF.

Optimal assignment method for mobile assistive robots using matching theory

Optimal assignment method for mobile assistive robots using matching theory

Optimal Task Offloading and Resource Allocation for C-NOMA Heterogeneous Air-Ground Integrated Power Internet of Things Networks

By combining information communication technology with power grid, the smart grid-oriented Power Internet of Things (PIoT) has become a critical technology to guarantee the safe and reliable power grid operation and improve system energy efficiency. Nevertheless, PIoT devices have only limited communication and computing resources since they are mostly deployed in remote areas that may be out of service coverage of existing terrestrial 5G networks. To overcome the resource limitation, we leverage Air-Ground Integrated C-NOMA Heterogeneous PIoT Networks (PAGIC HetNets), and study the core challenges in PAGIC HetNets. As PIoT devices are normally powered by battery, we aim at minimizing the energy consumption of PIoT devices and thoroughly investigate the problem of task offloading and resource allocation with minimal energy consumption. This problem belongs to a mixed integer nonlinear programming (MINLP) with extra difficulty that the long-term queuing delay and short-term constraints are coupled. To tackle the difficulty, we use Lyapunov optimization to transform this hard problem into three subproblems. The first subproblem is task splitting and local computing resource assignment at the PAGIC user side, which we solve with the Lagrangian multiplier method. The second subproblem is queue-aware channel reusing, and matching theory is adopted to solve it. The third subproblem is optimizing the aerial server resource allocation, for which we propose a greedy-based solution. Numerical simulations demonstrate that our approach can obtain excellent performance in terms of energy consumption, spectrum efficiency, task backlog, and queuing delay with lower complexity compared with several benchmark methods.

Analysis of the synergistic antifungal mechanism of small molecular combinations of essential oils at the molecular level

The bacteriostatic concentration of essential oil (EO) in practical application is usually higher than the flavor threshold, resulting in a lack of balance between bacteriostatic concentration and flavor, which has become the bottleneck of its application in the field of agriculture products. One of the effective ways to solve this problem is the synergistic antibacterial effect of the active components of EO. In this paper, molecular docking , independent gradient model (IGM) and symmetric matching perturbation theory (SAPT) are combined for the first time to investigated the molecular mechanism of eugenol and citral small molecules (E AC ) against Aspergillus niger . The results show that E AC can combine with β-(1,3)-glucan synthase and chitin synthase proteins, and then destroy the integrity of cell wall, in which the trans -citral has the best affinity with these two enzyme proteins. In addition, E AC can bind to tryptophan , tyrosine and phenylalanine in cell membrane. The binding of citral small molecules to these three amino acids is mainly hydrogen bond, while the binding force of eugenol to them is mainly van der Waals force or π-π interaction. Finally, the synergistic antifungal effect of E AC was confirmed by the damage of membrane proteins and the leakage of cell contents. In this combination, citral binds to the cell wall, which promotes the interaction between eugenol and cell membrane, and finally leads to the serious destruction of cell membrane. The above results show that E AC has the potential to be developed into a new type of agriculture products preservative with synergistic antifungal effect. • Eugenol and citral (E AC ) can combine with chitin synthase and β-(1,3)-glucan synthase to destroy the integrity of cell wall. • Trans-Citral has the best affinity with chitin synthase and β-(1,3)-glucan synthase. • Static electricity is the main contribution to the stability of essential oils molecules and amino acids. • The E AC could cause damages to Aspergillus niger cell membrane that led to a loss of cell viability.

A Polarization-Insensitive Broadband Terahertz Absorber Using Patterned Graphene.

A polarization-insensitive broadband terahertz absorber with a sandwich structure of metal−dielectric-graphene is designed and simulated. The graphene is patterned as an array of graphene square blocks with circular apertures. The results of the simulations and theoretical analysis show that the absorption exceeds 99% from 0.93 to 1.65 THz while 90% from 0.80 to 1.87 THz, and a broad relative bandwidth of 80.2% is achieved. The absorption performance is passively enhanced by altering physical dimensions of the graphene pattern and actively adjusted by changing the chemical potential of graphene. When the chemical potential increases from 0.1 eV to 0.7 eV, the corresponding terahertz absorption increases from 59.1% to 99%. The mechanism of absorption is disclosed by analyzing the impedance matching theory and distribution of electric-field intensity. In addition, different polarization modes and incident angles are also studied. The proposed absorber has the superiorities of broad relative bandwidth, high absorption rate, polarization insensitivity, and a wide incident angle, which offers some potential applications in the field of terahertz technology such as imaging, detection, and cloaking.

Thermo-optic modulator based on vanadium dioxide and nonlinear Kerr medium in terahertz region

Three-layer design of multi-functional terahertz (THz) metamaterials is proposed and numerically investigated, where the nonlinear Kerr-media is sandwiched between the phase change material of vanadium dioxide (VO2). Owing to the unique picosecond response of VO2 at different temperature, a high transmission is achieved before the phase transformation. When the vanadium dioxide is in the metallic phase, three band perfect absorption exist in the MIM structure. To fully dig out such high absorption, the impedance matching and effective medium theory are taken to obtain the effective dielectric and permeability. The underlying physical mechanism is further investigated with the normalized electric and magnetic field distribution at each resonant peak. In addition, a switcher is realized when the external pump light is utilized to irradiate nonlinear Kerr-media and its high sensing capability is explored with different Kerr medium. Therefore, our dynamic tunable modulator paves a new way in the design of tunable THz modulators, sensors and switchers.

Dynamically electrical/thermal-tunable perfect absorber for a high-performance terahertz modulation.

We present a high-performance functional perfect absorber in a wide range of terahertz (THz) wave based on a hybrid structure of graphene and vanadium dioxide (VO2) resonators. Dynamically electrical and thermal tunable absorption is achieved due to the management on the resonant properties via the external surroundings. Multifunctional manipulations can be further realized within such absorber platform. For instance, a wide-frequency terahertz perfect absorber with the operation frequency range covering from 1.594 THz to 3.272 THz can be realized when the conductivity of VO2 is set to 100000 S/m (metal phase) and the Fermi level of graphene is 0.01 eV. The absorption can be dynamically changed from 0 to 99.98% and in verse by adjusting the conductivity of VO2. The impedance matching theory is introduced to analyze and elucidate the wideband absorption rate. In addition, the absorber can be changed from wideband absorption to dual-band absorption by adjusting the Fermi level of graphene from 0.01 eV to 0.7 eV when the conductivity of VO2 is fixed at 100000 S/m. Besides, the analysis of the chiral characteristics of the helical structure shows that the extinction cross-section has a circular dichroic response under the excitation of two different circularly polarized lights (CPL). Our study proposes approaches to manipulate the wide-band terahertz wave with multiple ways, paving the way for the development of technologies in the fields of switches, modulators, and imaging devices.

Assortative matching in merging firms’ stock price informativeness

ABSTRACT Developed upon the assortative matching theory and recent studies that merging firms are matched on diverse firm characteristics and policies, this paper examines whether they also match in stock price informativeness. Our study shows that assortative matching between the acquirer and target firms’ stock price informativeness increases the probability of deal initiation. It also increases the likelihood that an M&A transaction is paid with stock and constructed as a negotiated merger. Finally, matched stock price informativeness increases merger wealth effect. This paper expands the application of the assortative matching theory in M&A literature from the perspective that stock price firm-specific information reflects firm fundamentals and policies.

Robust resource allocation algorithm in SWIPT-based D2D networks

To improve the operation lifetime of devices and the anti-interference capability of complex electromagnetic environments in device-to-device (D2D) networks, an energy-efficient maximization resource allocation algorithm was proposed for simultaneous wireless information and power transfer (SWIPT)-based D2D networks. Considering the constraints of users' minimum rate, minimum harvested energy, power splitting, and channel allocation, a robust energy-efficient resource allocation model was formulated by jointly optimizing the transmit power, subchannel coefficients, and the power splitting factor. The original NP-hard problem was converted into a deterministic and convex problem by using Dinkelbach's method and the worst-case approach, where the closed-form solutions were obtained by using the matching theory and Lagrange dual theory. Simulation results demonstrated that the proposed algorithm exhibited better robustness and higher energy efficiency.

Resource Allocation and Computation Offloading in a Millimeter-Wave Train-Ground Network

In this paper, we consider an mmWave-based train-ground communication system in the high-speed railway (HSR) scenario, where the computation tasks of users can be partially offloaded to the rail-side base station (BS) or the mobile relays (MRs) deployed on the roof of the train. The MRs operate in the full-duplex (FD) mode to achieve high spectrum utilization. We formulate the problem of minimizing the average task execution latency of all users, under local device and MRs energy consumption constraints. We propose a joint resource allocation and computation offloading scheme (JRACO) to solve the problem. It consists of a resource allocation and computation offloading (RACO) algorithm and an MR Energy constraint algorithm. RACO utilizes the matching game theory to iterate between two subproblems, i.e., data segmentation and user association and sub-channel allocation. With the RACO results, the MR energy constraint algorithm ensures that the MR energy consumption constraint is satisfied. Extensive simulations validate that JRACO can effectively reduce the average latency and increase the number of served users compared with three baseline schemes.

CoMap: An efficient virtual network re-mapping strategy based on coalitional matching theory

Virtualization of resources has been adopted in different environments such as wireless sensor networks (WSN), 5G networks, Fog computing, Internet of Things (IoT), and traditional data center (DC) networks. In DC networks, virtualized resources are provisioned as virtual networks (VNs), which comprise multiple communicating virtual machines (VMs) and virtual links (VLs) capturing their communication dependencies. However these virtual components, i.e., VMs and VLs, often experience fluctuating resource demands and require dynamic re-embedding as part of the management activities undertaken by the service providers (SPs). This paper focuses on addressing the issue of resource re-embedding via solution components (SCs), where a SC comprises a VM and its attached VLs, with either the VM and/or at least one of the VLs facing resource expansion. In fact, the resource provisioning problem for VNs is proven to be NP -Hard. Further, the requirement of distributed allocation of VMs of the VNs across the servers to avoid single point failure and enhance the survivability adds to the existing complexity. We propose a framework called CoMap that aims to generate an efficient relocation plan in polynomial time for VNs to reduce the re-embedding costs and improve the utilization of DC servers. The overall problem is modeled as a one-to-many matching game with coalition formation at the servers. Simulation results confirm a 32% average reduction in re-embedding cost and a 69% improvement in the average server utilization compared to the baseline algorithms.

Dual-band/ultra-broadband switchable terahertz metamaterial absorber based on vanadium dioxide and graphene

A dual-band/ultra-broadband switchable terahertz absorber based on vanadium dioxide (VO2) and graphene is proposed in this article. By controlling the properties of VO2 and graphene, the operation mode of the absorber can be switched between dual-band and ultra-wideband absorption. The simulation results show that the absorber works in the dual-band absorption mode when VO2 is in the insulating state and the Fermi energy level of graphene is 1.5 eV. The absorptivity are 99.4% and 99.8% at 1.08 and 3.52 THz, respectively. The frequency position of the absorption peaks can be switched by regulating the Fermi energy level of graphene. While the VO2 is transitioned to the metallic state and the Fermi energy level of graphene is 0.05 eV, the absorber operates in the ultra-broadband absorption mode with the absorptivity over 90% in the range 0.94–4.31 THz, and the relative absorption bandwidth reaches 128%. In addition, the working principle of the proposed absorber is analyzed by impedance matching theory and electric field distribution. Based on these characteristics, the proposed metamaterial absorber is expected to be used in the terahertz bio-detection and imaging fields.

Absorption enhancement in terahertz region by cross-shaped grating

Cross-shaped silicon-doped arrays are proposed for ultra-broadband absorber in the terahertz region, which consists of periodic Si/SiO2 microstructure. The cross-shaped silicon-doped absorber has a maximum absorption of over 99.9% and a relative bandwidth for absorption over 95% is 147% (0.96–6.24 THz). In this work, the absorber has better absorption bandwidth, center frequency, and relative bandwidth ratio than the various reference absorbers. The physical mechanism of the structure to achieve broadband absorption is explained by studying the electric field distribution. Furthermore, the ultra-broadband absorption characteristics of the absorber is demonstrated well by impedance matching theory. Finally, the effects of polarization angle, incident angle, angular rotation, and structural parameters on the absorption performance of the target structure are analyzed in detail, demonstrating that the structure has properties such as polarization-independent, wide-angle absorption and good process tolerance.

Capturing constrained constructor patterns in matching logic

Reachability logic for rewrite theories consists of a specification of system states that are given by constrained constructor patterns, a transition relation that is given by a rewrite theory, and reachability properties expressed as pairs of state specifications. Matching logic has been recently proposed as a unifying foundation for programming languages, specification and verification. It is known that reachability properties can be naturally expressed in matching logic. In this paper, we show that constrained constructor patterns can be faithfully specified as a matching logic theory. As a result, we obtain a full encoding of reachability logic for rewrite theories as matching logic theories, by combining the two encodings. We also show that the main properties of constrained constructor patterns can be specified and proved within matching logic, using the existing proof system.

Selection Strategies and Organizational Management in the Private Sector: Applying the Matching Theory in the Recruitment Process

The study examined selection strategies and organizational management in the private sector: applying the matching theory in the recruitment process. The population of study is the staff of the 50 selected organizations who were administered structured questionnaire. The Taro Yamane's formular for finite population was employed to achieve the 350 sample size used for the study. Correlation and Multiple regressions analyses were used to analyze primary data generated from the field and test thetwo formulated hypotheses. The study found that selection strategies had positive and significant effects on organizational management or performance in the selected hotels in Nigeria. It therefore concludes that selection strategies affect the management and performance of organizations. The paper recommends that more attention should be given to selection procedures/strategies in the recruitment process since they help to get the right and qualified persons for the vacant jobs in an organisation.And that selection of candidates should be anchored on merit, competence and similar job characteristic factors as they will improve employee's performance.

Resource Allocation in STAR-RIS-Aided Networks: OMA and NOMA

Simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is a promising technology that aids in achieving full-space coverage on both sides of the surface, by splitting the incident signal into transmitted and reflected signals. This paper investigates the resource allocation problem in a STAR-RIS-assisted multi-carrier communication networks. To maximize the system sum-rate, a joint optimization problem comprising of the channel assignment, power allocation, and transmission and reflection beamforming at the STAR-RIS for orthogonal multiple access (OMA) is first formulated. To solve this challenging problem, we first propose a channel assignment scheme utilizing matching theory and then invoke the alternating optimization-based method to optimize the resource allocation policy and beamforming vectors iteratively. Furthermore, the sum-rate maximization problem for non-orthogonal multiple access (NOMA) with flexible decoding orders is investigated. To efficiently solve it, we first propose a location-based matching algorithm to determine the sub-channel assignment, where a transmitted user and a reflected user are grouped on a sub-channel. Based on this <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">transmission-and-reflection</i> sub-channel assignment strategy, a three-step approach is proposed, which involves the optimization of decoding orders, beamforming-coefficient vectors, and power allocation, by employing semidefinite programming, convex upper bound approximation, and geometry programming, respectively. Numerical results unveil that: 1) For OMA, a general design that includes the same-side user-pairing for channel assignment is preferable, whereas for NOMA, the proposed transmission-and-reflection scheme can achieve comparable performance to the exhaustive search-based algorithm. 2) The STAR-RIS-aided NOMA network significantly outperforms networks employing conventional RISs and OMA.