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Improving green total factor productivity (GTFP) is an important theme. Whether collaborative agglomeration between logistics industry and manufacturing (LMCA) can effectively promote GTFP is worth further research. Based on the panel data of 284 cities in China from 2005 to 2018, GTFP is calculated by using the Biennial Malmquist-Luenberger productivity index (BMLPI), and this research investigates the impact of LMCA on GTFP by adopting the spatial Durbin model (SDM) and threshold regressive model (TRM). First, LMCA plays a significant role in promoting the improvement of GTFP in the local and surrounding areas through the knowledge spillover effect, scale economy effect, resource allocation effect and symbiotic economic effect, and the spillover effect is greater than the local effect. Second, the positive direct effect of LMCA on GTFP comes mainly from technological progress, and the positive indirect effect of LMCA on GTFP comes mainly from the positive spillover effect of technological progress and technical efficiency improvement. Finally, the Williamson hypothesis exists significantly in the collaborative agglomeration scenario of the logistics industry and manufacturing of China. With the improvement of the level of economic development, the impact of LMCA on GTFP changes from insignificant to promoting. However, when it is further improved, the promoting effect turns into an inhibiting effect, and this change is dominated mainly by the impact of LMCA on technical change.

Cantilever current sensors (CCS) have received increasing attention recently because of a passive sensing signal correlating to a linear detecting one. When a two-wire appliance is energized however, the distance between the cantilever and the two-wire appliance will become a time variable, which will undermine the above linear relationship. As a result, a nonlinear error is generated, and the measurement accuracy is thus decreased. The larger the amplitude of the cantilever is, the greater the nonlinear error is. In this study, a nonlinear error correction scheme is proposed for the first time without decreasing the sensitivity. Since the nonlinear error can be decreased by increasing the initial distance, while the sensitivity of the cantilever current sensor (CCS) is also decreased. Therefore, it is necessary to compensate for the decrease in the sensitivity by increasing the magnetic induction intensity of the magnet located on the cantilever. When the magnetic induction intensity is increased by 3 times, the initial distance can be increased from 3.5 mm to 5.5mm while maintaining the same sensitivity, and the nonlinear error is decreased from 47% to 32%. The proposed correction scheme is proven to be valid for decreasing the nonlinearity error while maintaining the sensitivity.

In our initial work of DTIP, a passive DC MEMS current sensor was proposed for single-wire or dual-wire current detection (DTIP2011, DTIP2012). A new type of oscillating MEMS DC current sensor, composed of an excitation element and a sensing element, was further proposed in DTIP2013. Since then, a series of studies, such as cantilever-based magnetic field sensor device (DTIP2014), corresponding relation between polarization and output voltage (DTIP2015), corresponding relationship between sensitivity and magnetic inductance (DTIP2017), magnetic field distribution surrounding three-phase four-wire appliances (DTIP2018), segmentation design and empirical analysis of piezoeletric layers (DTIP2018), as well as threshold-triggered current sensing (DTIP2019), have been carried out from different aspects. This work however, is oriented to realize an IEEE802.11g protocol compliant integratable dual-frequency coaxial microstrip antenna for wireless sensor networks. The newly designed antenna can be operated under two frequency bands of 2.45GHz and 5.2GHz, meeting the new physical layer standard IEEE802.11g emerged in recent years. A wireless cantilever current sensor (WCCS) is conceptualized to be an integration of a magnetic cantilever for sensing currents and a dual-frequency coaxial microstrip antenna for transmitting signals.

This paper proposes a new high-frequency narrow-band filtering mechanism using the internal resonance of an inverted T-shaped resonant structure. The proposed filtering mechanism is theoretically analyzed by combining the multi-scale method with the numerical iterative algorithm. For potential narrow-band filtering application, the influence laws of parameters related to the inverted T-shaped resonant structure on the internal resonance response characteristics are systematically studied. Two possible filtering systems integrated respectively with MEMS Switch and Double Frequency Circuit are further considered and discussed. The above two filtering systems have advantages of a good amplitude stability, a clear edge distribution in the passband frequency domain, and a strong suppression ability outside the passband frequency domain.

This paper, mainly reports a coupled cantilever structure applicable to mass or gas sensing applications with a higher resolution in a wider coupling range. Based on the coupled cantilevers with different rectangle geometry, we design a π-shaped coupled cantilever structure with triple frequency ratio, which provides mass or gas sensing with larger adsorption area. In the present work, internal resonance characteristics of the proposed structure are studied with different mass perturbations, and the coupling tongue characteristics with respect to the coupling range are further evaluated. Compared to that of the rectangular coupled cantilevers, on the one hand, a wider coupling range under the same applied voltage can be obtained, while on the other hand, a higher proportion of the third harmonic indicates a better resolution. The above preliminarily reveals the potential superiority of the internal resonant oscillation observed in the proposed the π-shaped coupled cantilever structure when applied to mass or gas sensing.

A centralized parameter model is established for the piezoelectric-magnetoelectric composite vibration energy convertor in the present work. The feasibility of the established model is comparatively studied with the theoretical calculation, the simulation results, as well as the experimental results. To achieve the optimal performance evaluated by the overall output power, the coupling strengths in three physical mechanisms of the piezoelectric, the magnetoelectric and the piezoelectric-magnetoelectric composite ones, are analyzed with considering and neglecting the structural differences respectively. And the coupling strengths are classified into three cases, such as the weak, the medium and the strong ones, determined by the ratio of the electromechanical coupling coefficient to the damping of the system. This work is believed to be greatly significant to the design of the PE-ME composite vibration energy convertor and self-powered devices.

Taking the long-span high-speed railway continuous girder bridge with the main span of 128m in China as an example, a reasonable finite element analysis bridge model adopting hyperboloid spherical seismic isolation bearings is established. Using nonlinear dynamic time history analysis method, the seismic mitigation performance of the bearings on high-speed railway bridges is studied. The parameters of the seismic isolation bearing, including the friction coefficient of the sliding surface and the radius of curvature, are optimized. Numerical analysis results show that: (1) Hyperboloid spherical seismic isolation bearings provide very good mitigation effect. (2)The bending moment at the bottom of the main pier and the displacement of the pier top both decrease first and then increase with the increase of the friction coefficient. The shear force at the bottom of the pier and the pier-beam relative displacement both decrease with the increase of the friction coefficient; The internal forces of the side pier bottom, the displacement of the pier top and the relative pier-beam displacement both decrease with the increase of the friction coefficient. (3)The internal force and the top displacement of each pier have a tendency to increase slowly with the increase of the radius of curvature. The change value is not obvious, and the pier-beam relative displacement increases with the increase of the radius of curvature. The bearing parameters should be determined both on the numerical analysis results and the requirements of the bearing structure size.

The influence of multi-point earthquake excitation on seismic mitigation and isolation control of high-speed railway extradosed cable-stayed bridge is studied. Taking the main bridge of yingshang super large bridge in Shangqiu-hefei-Hangzhou high speed railway as an example, finite element calculation model is established, and nonlinear dynamic time history analysis method is used. the calculation results of internal forces and displacements of the bridge are obtained when the seismic wave velocity is 250m/s, 500m/s, 750m/s, 1500m/s, 2500m/s and infinite (equivalent to uniform excitation) by using common bearing, viscous damper, lock-up devices and hyperboloid spherical seismic isolation bearings, respectively. The results show that: (1) The seismic response of the bridge is different under the action of different seismic wave velocity, when the wave velocity is 750 m/s, the internal force and displacement of the structure reach the peak value; (2) When the traveling wave effect is considered, the internal forces and displacements of the piers with three types of seismic isolation devices and common bearings have an increasing tendency; (3) the viscous damper and the hyperboloid spherical seismic isolation bearings have better seismic performance, while the lock-up devices increase the overall stiffness of the bridge, and thus amplify the internal force response of the structure.

Capacitor voltage balancing strategy for Submodules (SMs) is one of the key technologies for modular multi-level converters(MMC). The conventional strategy has the problems of large computation and high switching frequency of devices. In order to solve these problems, a mark and operation voltage balancing strategy (MOVBS) is proposed. This strategy marks SMs with two different labels according to the amplitude of capacitor voltage of SMs and current direction of arms, then do sorting and selecting operations to SMs based on the marking results. It reduces sorting times, switching frequency and power loss of devices. For capacitor voltage sorting process, a binary radix sorting algorithm(BRSA) is proposed to improve sorting speed and efficiency of MOVBS. Finally, the feasibility and effectiveness of the MOVBS is verified with a 11-level MMC-HVDC simulation model created in Matlab/Simulink.

In view of the traditional tram energy consumption analysis method be lack of judge and analysis of abnormal data as well as is difficult to effectively discover the characteristics of energy consumption data and the potential relationship between data, an integration method of tramcar energy consumption analysis with control charts and grey correlation analysis is proposed. By using the control chart, the fluctuation of energy consumption data is analyzed, and the influence degree of each factor on energy consumption data is analyzed by grey relational analysis. The simulation experiment is carried out by using the energy consumption data of Guangzhou tram cars. The result shows that the tram energy consumption analysis method proposed not only can analyze the characteristics of all energy consumption data and mine potential relations among data, but also can monitor the fluctuation of energy consumption data and identify the abnormal energy consumption data as well as related factors that affect energy consumption. providing auxiliary decision-making for energy saving of tram system, which can provide some reference for the analysis of the energy consumption data of the running tramcar.

In practical engineering applications, capacitor voltage sorting of Modular Multilevel Converter (MMC) in Power Electronic Transformer (PET) input stage is a huge engineering difficulty. To solve the problems of traditional voltage balancing sorting algorithm, such as high switching frequency, large amount of computation and large switching loss, an optimizing voltage balancing method is proposed to reduce time complexity and switching frequency. Firstly, Merge sort is used to select the appropriate elements as reference values of the randomized-select algorithm, and then the randomized-select algorithm is used for quick sorting. On this basis, the reordering factor is introduced. When the difference of capacitance voltage between sub-modules (SMs) is small, it avoids reordering and keeps trigger pulse unchanged; otherwise, it quickly reorders. Selective sorting of MMC controllers not only further reduces the computational complexity of the controllers, but also effectively reduces switching losses. Finally, the feasibility and validity of the proposed optimization method are verified with MATLAB simulation.

Emerging applications today operate on increasingly larger data sets, and as a result, the memory subsystem is prone to be a bottleneck in bandwidth and capacity. Many of these applications store data based on real world phenomena which often have continuity properties and can be approximated by mathematical functions. In this work, we view computer memory abstractly as a set of functions that map each address input to a data output. We propose Approximate Algebraic Memory (A2M), a specialized memory model that uses finite degree polynomials to approximate ranges of memory content with the desired properties. Specifically, A2M uses dedicated hardware to derive and store polynomial coefficients rather than memory data. In error resilient workloads, the benefits of this design is threefold: (1) high ratio memory compression, (2) high bandwidth accesses, and (3) direct computation on memory. We evaluate A2M’s potential as an on-chip structure for general-purpose processors, and as a specialized read-only memory for neural network accelerators. Our results show that for CPU workloads, A2M yields minimal error (< 1%) at a fixed compression ratio of 16, and improves performance by 11.3% on average.

GH4169 alloy turbine disk is one of the critical components in hot end of the aeroengine. It is prone to cracks, especially surface cracks which can significantly undermine the quality of disk, resulting in fatigue fracture and thereby catastrophic failures. In this paper, eddy current testing (ECT) of surface cracks was investigated through simulations based on CIVA and experiments. The ECT probes in different configurations and parameters were modelled and impedance curves were computed. The parameter and structure of probe was determined by analyzing the signal decay rate and defect resolution. Following this, experimental investigation was carried out to verify the simulation results. It could be found that experimental results matched well with simulation results and the probe designed via simulations was applicable. The related results from both simulations and experiments are supportive of ECT of surface cracks on GH4169 turbine disk.

An improved design of a dual-band circularly polarized (CP) square loop antenna under even-mode resonance is presented in this paper. The designed antenna is fed by a pair of orthogonal dipole launcher with fork-like stubs and connected with a simple balun above the ground plane. Four L-shaped tuning stubs can simultaneously excite the first two, odd-order even-modes. An approximate dual-band ratio design formula is also deduced by using data fitting technique. The proposed antenna exhibits identical CP sensing at its two resonant modes. The proposed approach is expected to get applications in dual-band circularly polarized antenna designs.

A coupled cantilever system, consisting of a low-frequency and a high-frequency cantilever was reported in DTIP2012 to study the synchronized region. While the doubled frequency response by the super-harmonic oscillation, the optimization of polymer-based synchronized structures, and SNR enhancement by internal resonance were demonstrated in DTIP2013, DTIP 2016 and DTIP2018 respectively.In this paper, we explore separate detection of two kinds of perturbations in coupled resonator system for the first time. Two cantilevers with a frequency ratio of 1:3 are coupled through an overhang. The low-frequency cantilever used for sensing is driven around its resonant frequency. The triple response is observed in the high-frequency cantilever used for detecting. The proposed oscillation system, not only enables frequency shift multiplication, but also accomplishes separate detection of two kinds of perturbations due to their different variation laws of vibration characteristics.

A passive type MEMS DC current sensor for monitoring the electricity consumption by either one-wire or two-wire appliance cord was proposed, micro-fabricated and tested in our past work (DTIP 2011, 2012). A novel oscillating type MEMS DC current sensor, comprised of both actuating and sensing elements, was further proposed for constant DC current measurement (DTIP2013). The relationship between magnetic induction and sensitivity of the DC current sensor was discussed both analytically and experimentally (DTIP2017). In this work, exploratory study on threshold-triggered AC current sensing mechanism by making use of bistability applicable to two-wire AC appliances is proposed in this work. It can monitor the AC current whether reaches a critical level when it is used for AC current. Only when the monitored amplitude of AC current reaches a preset threshold, the bistable piezoelectric cantilever sensing system will transform from intrawell oscillations to interwell oscillations, realize snap-through and give out a high output.

The LCLC resonant converters are widely used in the Electronic Power Conditioner (EPC) in a Travelling-wave Tube Amplifier (TWTA) due to the advantage of Zero-Voltage-Switching (ZVS) and Zero-Current-Switching (ZCS). However, in the physical circuit, problems such as non-Zero-Current-Switching and reverse resonant current appear and the efficiency decreases. Based on the working principles of the LCLC resonant converters, this paper presents the method to remove the reverse resonant current and the non-zero switching. Furthermore, an empirical data is given to guide the design of the converter. Finally, the analysis is validated by the simulations and experimental results.

This paper proposes a new working mode of the high frequency Flyback converter for the high-voltage low-power applications, such as atomic clock, ion analysers, high voltage ignition system, vacuum electronic devices etc. With the proposed working mode, the main switch of the Flyback converter can achieve Zero Voltage Switching (ZVS) without extra auxiliary switch. Due to the advantage of ZVS, the Flyback converter can operate under high frequency and high efficiency conditions. As a result, the volume of the passive components can be reduced and the power density of the converter can be improved. The proposed working mode of high-frequency Flyback converter is validated by simulations and experiments.

The Yellow River Road-cum-Railway Bridge of Shijiazhuang-Jinan Passenger Dedicated Line is a large-span, long connected continuous suspension reinforced steel truss bridge. The seismic performance standard is high, so the internal force of the fixed pier under rarely occurred earthquake is large. It's difficult to conduct seimic design, and the reasonable seismic mitigation system should be studied. Through the setup of lock-up devices in the movable piers, the reasonable scheme is obtained, and the position and caculation parameters are optimized. Research conclusions are as follows: (1) The total stiffeness of the bridge is increased owning to the adopting of lock-up devices. But through the sharing of the movable piers, the good mitigation ratios are all obtained under different setup schemes. (2) For the pier with lock-up devices with relatively low height, and the number of neighboring movable piers without lock-up devices is large, the seimic response could be larger than the fixed pier. (3) For long connected road-cum-railway bridge, the setup position and number should be optimized, considering both the seismic mitigation ratios of internal forces and displacements. Besides, the maximum magnification factors and damping tonnage should also be considered. (4) For the road-cum-railway bridge, the pier-beam relative displacements of the railway and highway floor should both be considered in order to control the displacement value of expansion joints of both floors.

Lightning strike and electromagnetic induction resulted from lightning pose a serious threat to the electronic equipment and weapons on the naval ship. Systematic protection design is therefore essential to reduce the probability of electrical equipment and weapons being damaged. In this paper, we discussed the whole ship direct-lightning protection scheme, combining the installation of lightning rods on top of masts as well as the direct lightning strike protection and reinforcement of the local high structures such as ship borne medium-wave and short-wave communication antennas and large radar antennas. The design plans that developing lightning induction protection from different levels such as the platform, system, equipment or subsystem are analysed. The contents and methods of relevant verification and assessment test are also discussed.

The physical memory capacity of servers is expected to increase drastically with the deployment of the forthcoming non-volatile memory technologies. This is a welcomed improvement for the emerging data-intensive applications. For such servers to be cost-effective, nonetheless, we must cost-effectively increase compute throughput and memory bandwidth commensurate with the increase in memory capacity without compromising the application readiness. Tackling this challenge, we present Memory Channel Network (MCN) architecture in this paper. Specifically, first, we propose an MCN DIMM, an extension of a buffered DIMM where a small but capable processor called MCN processor is integrated with a buffer device on the DIMM for near-memory processing. Second, we implement device drivers to give the host and MCN processors in a server an illusion that they are independent heterogeneous nodes connected through an Ethernet link. These allow the host and MCN processors in a server to run a given data-intensive application together based on popular distributed computing frameworks such as MPI and Spark without any change in the host processor hardware and its application software, while offering the benefits of high-bandwidth and low-latency communication between the host and MCN processors over the memory channels. As such, MCN can serve as an application-transparent framework which can seamlessly unify the near-memory processing within a server and the distributed computing across such servers for data-intensive applications. Our simulation running the full software stack shows that a server with 8 MCN DIMMs offers 4.56 x higher throughput and consume 47.5% less energy than a cluster with 9 conventional nodes connected through Ethernet links, as it facilitates up to 8.17 x higher aggregate DRAM bandwidth utilization. Lastly, we demonstrate the feasibility of MCN with an IBM POWER8 system and an experimental buffered DIMM.

As an emerging urban public transport, energy storage trams are the major electricity consumers in the city. Most of the trams use distributed power supply, and the traction substations are derived from the urban medium-voltage network. Therefore, it is of great significance to establish a model that can predict the energy consumption distribution at each site. Existing models mostly use regression methods, focusing on analyzing the correlation between various influencing factors and energy consumption, and forecasting the total energy consumption of tram lines through a large amount of statistical data. Analyze the complete operation process of the tram between the stations, use MATLAB/Simulink to build its operation model, simulate the operating conditions of the tram, and obtain the traction energy consumption model of the energy storage tram. Regarding the vehicle air conditioning energy consumption model, the vehicle energy consumption model was further obtained. By verifying the model with the existing operating data, the error is within the allowable range, which has certain practicality and provides a basis for energy-saving analysis.

A novel multi-beam antenna based on Butler matrix is designed and realized. In this paper, Butler matrix adopts the substrate integrated waveguide and double layer technology to realize the miniaturization of the network, and the two-layer directional coupler achieves good matching and better flatness in amplitude and phase by using multiple slots, besides, the edge gradient short holes of short slot coupler is adopted to better ensure the equipartition of energy, and inhibit the emergence of TE30. The proposed multi-beam antenna has operation frequency range of 8.0 to 8.5GHz with perfect port matching performance. The maximum gain of the intermediate beam of the antenna reaches 11.2dBi, and the maximum gain of the beam on both sides reaches 10.0dBi with ± 38 ° beam point.

A network model with multiple derivative couplings and different dimensions of output and input vectors is investigated in this paper. The problem of passivity for the proposed network model is analyzed by utilizing some inequality techniques and Lyapunov functional method. Moreover, by employing adaptive feedback control strategy, some sufficient conditions for guaranteeing passivity of complex dynamical network with multiple derivative couplings (CDNMDC) are obtained. In the end, we give an example to verify the effectiveness of the results.

The effects of geometrical design of the coupling overhang, cantilever length, as well as the number of identical coupled cantilevers on the magnitude enhancement with a small mass perturbation were previously reported in DTIP 2011. And the effect of material damping induced by the internal friction loss was studied in DTIP 2017. However, this paper has made an analytical study on mass perturbation in a mode-localized four-cantilever array made of copper, whose amplitude ratio is higher than previous cantilever arrays. In light of vibration eigenstate changes, the sensitivity is higher when mass is applied on the side resonator (NO.1 or NO. 4). The conclusion can be analytically determined by simulation results. To further analyze sensitivity, amplitude ratio between NO.1 and NO.4 resonator (NO.2 and NO.3 resonator) has been investigated. In this paper, the mode-localized cantilever array has a wide range of applications such as in measuring electric field force, magnetic force etc.

A coupled cantilever system, consisting of a low- frequency and a high-frequency cantilever was reported in DTIP2012 to study the synchronized region. While the doubled frequency response by the super-harmonic oscillation and optimization of polymer-based synchronized structures were demonstrated in DTIP2013 and DTIP 2016. In this paper, we focus on internal resonance in coupled resonator system for the first time. Two cantilevers with a frequency ratio of 1:3 are coupled through an overhang. The low-frequency cantilever used for sensing is driven around its resonant frequency. The third harmonic response is observed in the high-frequency cantilever used for detecting. The proposed oscillation system, not only enables frequency shift multiplication, but also alleviates environmental damping effects on the detecting oscillator. Moreover, some other coupled resonator systems are further designed to demonstrate SNR enhancement. These coupled resonator systems possess the advantage of easy to realize internal resonance and exhibit improved sensitivity for sensor device applications.

In this paper, the piezoelectric layer segmentation design, which is based on the cantilever structure, has been proposed to increase the output voltage. The piezoelectric layer of the cantilever structure is firstly divided into equal parts with the same number. A mathematical model of the output voltage in the horizontal, vertical and oblique directions has been established. Subsequently, COMSOL Multi-physics software is used to verify the theoretical derivation. The simulation results show that regardless of the segmentation angle, the output voltage is proportional to the number of slices when the piezoelectric layer is equally divided into the same number of pieces. As for the equally wide-divided piezoelectric layer, the segmentation along the direction vertical to diagonal direction can obtain the greatest output voltage value.

As for the industrial area, the control of VOCs emission has attracted a lot of attentions of researchers for several decades. Appropriate control strategies are fundamental tools to restrain the emission of VOCs. Based on empirical data extracted from the complete set of sources, control strategies for reducing VOCs emission process are proposed in this paper, which are obtained by performing numerical analyses. Empirical data are applied into the proof of theoretical results. Complete sources including industrial source, traffic source, living source and agricultural source are considered. The impacts of output value of general equipment in the industrial source, passenger throughput in traffic source, the size of population in living source and agricultural source on VOCs emissions are discussed. Additionally, control strategies for VOCs emissions are summarized by analyzing extremum of characteristic values obtained from sample sets. Finally, the features of various VOCs emission sources are concluded to guide the adjustment of treatment process, especially the treatment equipment of VOCs.

Two compact balanced filters using coupled slotline structure are presented in this paper with intrinsic common-mode (CM) rejection and enhanced differential-mode (DM) out-of-band response. By properly designing the proposed U2 folded stepped-impedance slotline resonators (SISRs), compact size and extended DM upper-stopband rejection could be achieved. Specifically, two balanced filters with second-order and third-order coupled slotline resonators (SRs) are implemented. Measured and simulated results are in approximate agreement with each other, showing inherent CM rejection and enhanced DM out-of-band performance such as improved selectivity, multiple transmission zeros (TZs) as well as extended upper stopband.

This paper firstly proposes a self-powered piezoelectric tri-axial accelerometer, based on the electromagnetic energy harvesting mechanism. Secondly, the structure of seismic mass is improved to harvest more power under the horizontal vibration. The optimized output power reaches 10mW under horizontal vibration at 100Hz, according to the simulation results. In the end, the loss of accuracy due to power-supply part is analyzed and an error compensation method is presented.

In this article, the joint detection in uplink are studied in Massive MIMO (Massive Multiple-input Multiple-output) system. This article will combine interference estimation with soft detection, and finally propose a new structure for joint detection in uplink based on 5G simulation test platform of NCRL (National Mobile Communications Research Laboratory of SEU) and analysis feasibility of the new structure and give out simulation results.

In this work, a passive and non-contact current detection method for three-phase four-wire appliances under symmetrical loads is proposed for the first time. The sensor consists of a piezoelectric cantilever with a permanent magnet mounted to its free end. When placed near appliances carrying AC currents, the magnet couples to the oscillating magnetic field around appliances, deflecting the cantilever and generating a sinusoidal voltage proportional to currents. In order to achieve a higher measurement sensitivity, the optimal location for magnet is determined by preliminary theoretical analysis and simulation method. The proposed low-power and non-invasive method, useful in real-time health monitoring of electrical equipment like three-phase motors, three-phase transformers and other related ones, is also applicable to future industry WSN.

This paper has presented an excitation circuit for self-oscillating fluxgate DC current sensors with symmetrical bi-excitation structures. It consists of two excitation windings, a multivibrator, an inverter, sampling resistors and an adder. The two sets of excitation currents will together produce circumferential magnetic fields in the ferromagnetic core. The strength of the magnetic field in the magnetic core is deduced according to the ampere-loop law. And it is proved that the excitation current is still in line with the average current model when the mutual inductance effect has been taken into account and the circuit parameters are symmetrical. A relevant simulation for the degree of the circuit parameters' influence has also been performed to verify the results.

A bistable energy harvester is proposed. It consists of cantilever couples, permanent magnets, as well as the intermediate slot, which can make cross beam accomplish horizontal movements to acquire two states. Each state corresponds to two bistable. Under external excitations, adjust the cross beam position to realize two states switch to acquire four bistable state. Because of this will broaden the frequency bandwidth and thus increase the harvested energy, which is expected to be applicable to self-powered lateral vibration sensor devices. After the simulation analysis, the energy collected by this part was improved by 193%. The bandwidth of the two subsystems corresponding to each state is widened by at least 20 Hz.

We present the synchronization phenomenon of magnetically coupled cantilevers for the first time. two kinds of magnetic coupling method are promoted. The first one takes advantage of electromagnetic induction phenomenon between permanent magnet and induction coil, which consists of a magnetic cantilever covered by permanent magnet blocks and a T-shape cantilever with a conductive rectangular ring in the free end. Theoretically there exists an internal force feedback loop, which is necessary for phase synchronization, meaning this contactless coupling method holds a great possibility to realize synchronization. Since magnetically realized synchronization of cantilevers is a barely researched field, we promote the second structure to do some numerical study, which uses direct magnet coupling of two permanent magnet blocks located in the free end of the two cantilevers. Numeric simulation of the solid-magnetic interaction coupling process is performed via COMSOL Multiphysics. From simulation result, we find out that there exist several frequency points that the frequency of the driven cantilever is exactly doubled as design, meaning that there is a great possibility that this is the very synchronization state we are searching for, yet more precise simulation and experimental result is needed to ensure that. Both design have a potential possibility to realize magnetic synchronization of cantilevers. The first design exhibits a great possibility that the cantilever can reach contactless synchronize theoretically. Yet the other design is more appropriate to perform preliminary stage numerical and experimental study to explore the unique physics phenomenon of magnetic synchronization of cantilevers so as to provide necessary information to perform the second stage of study using the first design.

A cantilever-based structure is proposed in this work for characterizing surface features of kinetic friction coefficients and surface roughness wavelengths. A cantilever, with a friction block on the free end of it to contact with target surfaces, is designed. Kinetic friction coefficients are measured by resonance frequency shifts of the cantilever, while surface roughness wavelengths are measured by the peak frequencies of friction-induced vibration of the cantilever. When the resonance frequency shifts $\Delta \omega \mathbf{R}$ reach a level of one hundred kilohertz, $\mu\mathbf{N}$ scale friction force and 0.001 scale kinetic friction coefficient detection can be achieved, while the contour mean width Rsm, correlated to the surface roughness wavelengths, are found to decrease from 181.4 to 78.5 with the vibration frequency increasing from 429.1 Hz to 1886.5 Hz. Comparing to traditional one, the proposed structure has advantage of being able to simultaneously characterize kinetic friction coefficients and surface roughness wavelengths, which can be used to sense very small changes in surface and is believed to be applicable to biomedical early warning.

In this paper, a optimization strategy is proposed to study the data acquisition and transmission in the wireless sensor network based upon intelligent ecological community. Considering the regression analysis method based on norm theory, a linear regression model was established on the measurement data to solve the various parameterized vectors of corresponding base functions. Then the algorithm and strategy of network data acquisition and transmission optimization are proposed, which can also reduce communication energy consumption. Finally the effectiveness of the algorithm was verified by the scene of temperature monitoring in the outdoor activity facilities.

A dual-frequency, circularly polarized (CP) square loop antenna under even-mode resonance is presented. The square loop antenna is diagonally fed by a fork-like dipole launcher. Four tuning stubs are symmetrically introduced near the current distribution nulls of the second odd-order resonant even-mode. In this way, the second odd-order even-mode is excited and dual-band circularly polarized characteristic can be realized. The dual-band behavior of the antenna is numerically studied and a closed-form formula is deduced. The preliminary result in this work is expected to be useful in future dual-band CP loop antenna designs.

In order to decrease the measurement error of piezoelectric-cantilever current sensor caused by position and orientation errors, a position and orientation correction scheme including an array of piezoelectric cantilever and a system of nonlinear equations is presented in this paper. By solving the system with the values of piezoelectric outputs, current to be measured can be derived. Results of experiments of passive sensing are presented, proving the validity of the proposed correction scheme. Theoretical analysis of active sensing gives insights to future research.