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The core–shell TiO2 nano-layer spheres were synthesized by hydrothermal method without surfactant, using tetraisopropyl titanate, diethylenetriamine and water as the capping agents. The structure of the products was characterized with X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscopy (SEM). The possible formation mechanism and electrocatalytic degradation characters of the products were also discussed.

Cross-efficiency evaluation in data envelopment analysis (DEA) is effective for evaluating the efficiency of decision-making units (DMUs). The use of cross-efficiency evaluation methods based on pr...

Lithium sulfur batteries (LSBs) have attracted tremendous attention owing to their high theoretical specific capacity and specific energy. However, their practical applications are hindered by poor cyclic life, mainly caused by polysulfide shuttling. The development of advanced materials to mitigate the polysulfide shuttling effect is urgently demanded. Metal-organic frameworks (MOFs) have been exploited as multifunctional materials for the decoration of separators owing to their high surface area, structural diversity, tunable pore size, and easy tailor ability. In this review, we aim to present the state-of-the-art MOF-based separators for LSBs. Particular attention is paid to the rational design (pore aperture, metal node, functionality, and dimension) of MOFs with enhanced ability for anchoring polysulfides and facilitating Li

The performance of zeolite membrane supports directly determines the synthesis performance and industrial application of zeolite membranes. In this study, a novel and high permeation SiC supports for NaA zeolite membrane were prepared by carrying out in situ reaction bonding at high temperature in the air atmosphere to coat the SiC particles with aluminum sol. The effects of process parameters on the formation of porous structure of SiC supports were systematically investigated, and the underlying mechanism was explored. During the sintering process, high-temperature Al2O3 from aluminum sol reacted with SiO2 generated by oxidation of the surface of SiC particles to form mullite, which exhibited excellent chemical stability and improved the mechanical properties and chemical stability of the supports. The porous SiC supports for zeolite membrane displayed obvious three-dimensional connected pore structure, with smooth inner surface of the pores and obvious connection neck between the particles. The porous SiC supports for zeolite membrane showed good in situ mullite bonding between the particles, and high permeability. It has a porosity of 36.3%, an average pore size of 1.42 µm and a bending strength of 32.4 MPa. All these figures indicate good comprehensive properties that are consistent with the rigorous requirements of zeolite membrane synthesis and industrial application.

Two-dimensional metal-organic nanosheets (2D MONs) are an emerging class of ultrathin, porous, and crystalline materials. The organic/inorganic hybrid nature offers MONs distinct advantages over other inorganic nanosheets in terms of diversity of organic ligands and metal notes. Compared to bulk three-dimensional metal-organic frameworks, 2D MONs possess merits of high density and readily accessible catalytic sites, reduced diffusion pathways for reactants/products, and fast electron transport. These features endow MONs with enhanced physical/chemical properties and are ideal for heterogeneous catalysis. In this Review, state-of-the-art synthetic methods for the fabrication of 2D MONs were summarized. The advances of 2D MONs-based materials for electrocatalysis and photocatalysis, including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO

Blade tip clearance (BTC) is one of the key factors affecting the efficiency and reliability of high performance turbomachinery such as heavy duty steam turbines, aircraft engines and other gas turbo machines. The self-adjusting ability of BTC according to the operation condition changing is important to meet the requirement of performance. In this paper, the principle and method of adjusting the BTC by controlling the axial displacement of the rotor were proposed and studied. The basic principle is that the BTC of the turbomachinery with a conical tail shroud will be affected by the axial displacement of rotor and thereby can be adjusted by controlling the axial position of rotor, which can be adjusted by the controllable oil pressure acting on the thrust bearing. To reach a higher control precision, lower noise and model perturbation, an adaptive quasi-sliding mode control (AQSMC) algorithm based on the disturbance observer (DOB) was designed, and numerical and experimental investigations were carried out. The numerical simulation results show that this algorithm can not only effectively suppress the disturbance, but also, compared with the general reaching law, effectively reduce the chattering and transient high gain switching effect of the closed-loop controller system and avoid the instability caused by the controller. Based on the DOB-AQSMC algorithm, the BTC was stabilized within 2 s with no overshoot and no misalignment in the test rig, and this algorithm achieves a better control performance than the proportion-integral-differential (PID) algorithm. These achievements can be used to push forward the intelligent turbomachinery development.

Wireless sensor nodes in wireless sensor networks are generally battery powered and it is usually hard to change their batteries. Therefore, energy saving has always been the basic critical problem of wireless sensor networks. In recent years, network coding has become a promising technology to improve network throughput, reduce transmission number, and save energy, which has great potential to solve the energy efficiency problem of wireless sensor networks. In addition, some network coding aware routings have been proposed. However, the network coding condition of existing network coding aware routings may experience the problem of false-coding effect in some scenarios, and usually neglect node energy, which greatly influences the energy efficiency performance. Therefore, existing network coding aware routings are not suitable for wireless sensor networks. This paper proposes network coding aware energy efficient routing (NAER) for wireless sensor networks. In NAER, universal network coding condition is presented and proved to avoid false-coding problem. Besides, combined with the coverage control and topology control mechanism at lower layer, cross layer coding opportunity discover mechanism is presented to increase coding opportunities. In addition, a network coding aware energy efficient routing metric (NERM) is presented, which takes coding opportunity, node energy, and link quality into account jointly. Simulation results demonstrate that NAER improves the accuracy of coding discovery mechanism, increases the number of coding opportunities, saves node’s energy consumption, and prolongs network lifetime.

Active control methods of rotordynamic stability for rotordynamic systems have been developed for many years, however effectively implementing these methods in real machines remains a significant challenge. With the goal of improving the performance of a back-to-back centrifugal compressor, a new integral electromagnetic actuator that combines the functions of an active magnetic bearing with a hole pattern seal is designed and used to replace the original balance piston of the machine. The structure design and assembly in the compressor are presented and an investigation on the seal performance and magnetic bearing forces is carried out. The results show that this innovative integral actuator can provide both sealing and vibration control, with two vibration feedback control methods experimentally validated for the elimination of oil whip, improving the rotordynamic stability of the machine.

The static and dynamic characteristics of tilting-pad thrust bearing (TPTB) considering the lubricant viscosity-temperature effect and pad elastic deformation are first analyzed by theoretical thermalelastohydrodynamic (TEHD) modeling. The TPTB test rig with electric oil pump is designed and built to apply axial loads and sinusoidal hydraulic excitation due to the opening changes in the overflow valve. An Instrumental Variable Filter (IVF) algorithm is developed to identify the TPTB stiffness and damping coefficients with pad pivot stiffness considered. Compared to the experimental results, the calculated TPTB temperature is more accurate after using the TEHD model. The TPTB stiffness and damping coefficients calculated by the pressure perturbation method are reasonably close to the experimental results with low-amplitude and low-frequency hydraulic excitation.

Synchronous contention-based medium access control (MAC) protocols play a vital role in the delay guarantee essentially required by many recent delay-sensitive applications. Great efforts have been made to improve the end-to-end delay by means of optimizing the medium access performance. However, their effectiveness is still constrained by the contradiction between reducing the collision probability and idle listening duration. Instead of traditional tradeoff strategies, developing a way to further alleviate the contradiction is definitely beneficial for further improving the medium access performance. To this end, a self-adaptive implicit contention window adjustment mechanism for SMAC (Sensor MAC) is proposed based on the investigation of the medium competition behavior impacting the medium access delay and delay jitter, from the perspective of any given contending node. We mathematically derive the expected medium access delay for revealing the strengths and weaknesses of typical dynamic contention window mechanisms. Moreover, it is discovered that their delay-oriented optimizing window only offers fairly limited improvement in the medium access performance since the uniformly random slot-selection mechanism results in high delay jitter and the contradiction between reducing the collision probability and idle listening duration. In order to overcome this drawback, furthermore, an optimization model of the node contention priority distribution is proposed to alleviate the aforementioned contradiction by means of optimizing slot-selection mechanism. Finally, a self-adaptive implicit contention window adjustment (SICA) mechanism is designed integrating delay-oriented optimizing contention window, contention priority optimization model with the estimation method of contenders' number. Through simulations in OMNeT++, the results demonstrate that the proposed SMAC-SICA outperforms its peers in terms of delay guarantee, energy efficiency and throughput.

To prevent the thrust bearing damage faults, the thrust bearing pad temperature and the static axial displacement variation are usually monitored and cared about, but axial vibration caused by axial dynamic excitation can also result in the severe rubbing. An electric oil pump system with overflow valve is designed on a similar industrial centrifugal compressor test-rig to apply the axial low-frequency excitation from 3 to 7 Hz, and the axial and radial vibration response amplitudes are analyzed. Then, the stiffness and damping coefficients of tilting-pad thrust bearing (TPTB) are identified by instrumental variable filter (IVF) algorithm to reveal the mechanism of TPTB dynamic characteristics affecting axial vibration. Finally, a fault case about surge and the rubbing of thrust bearing is studied. Compared with axial vibration, radial vibration does not directly correlate to axial excitation, and the axial frequency spectrum is an effective method to diagnose axial displacement faults; the static axial load, the dynamic excitation amplitude and the excitation frequency all exert influence on thrust bearing dynamic characteristics and axial vibration response. The research results can guide the design of thrust bearings and help to diagnose the axial displacement faults, while the test device and method can be used to measure the static and dynamic characteristics of thrust bearings.

Energy efficiency is a critical problem for wireless sensor networks. In past decades, network coding has been proved as a promising technology to reduce the number of transmissions, save energy, and improve network throughput, especially suitable for the wireless network that motivates the emergence of network coding aware routings. However, existing network coding aware routings have the failure decoding problem, because of defective network coding conditions. On the other hand, existing network coding aware routings usually consider the ideal traffic scheduling and neglect nodes' energy and load which are important to wireless sensor networks. Therefore, it is not appropriate to directly apply existing network coding aware routings in wireless sensor networks. Regarding the problems above problems, this paper proposes traffic-shaped network coding aware routing (TSCAR) for wireless sensor networks. In the TSCAR, a universal network coding condition is presented to solve the false decoding problem. And traffic shaping mechanism is proposed to shape the traffic of different flows to create more coding actions when coding opportunities exist. In addition, network calculus is used to analyze the delay of the TSCAR. Besides, a coding, load, and energy aware routing metrics are proposed to evaluate the discovered paths. Extensive simulation results demonstrate that the TSCAR increases the number of coding opportunities and the proportion of coded packets, improves network throughput, and extends the network lifetime of wireless sensor networks.

Network coding possesses great potentiality in promoting wireless multi-hop network throughput performance. Network coding applied in routings includes intra-flow network coding and inter-flow network coding. The aim of intra-flow network coding is to promote wireless transmissions reliability. For inter-flow network coding, its purpose is to reduce transmission number and rise network throughput. In this paper, an inter-flow and intra-flow network coding aware routing (RACR) is designed for wireless multi-hop network to make use of the benefits of both intra-flow and inter-flow network coding. RACR actively detects inter-flow coding opportunities on the basis of network coding condition in routing discovery in order to discover more coding opportunities. In addition, intra-flow network coding is exploited at source node of each flow to ensure correct inter-flow decoding and to avoid the dependence on the receiving of any specific packet. The simulation results on NS2 confirm that RACR can reduce transmissions times and rise the throughput of network.

Network coding is a technology with great potentiality in improving wireless multi-hop network throughput. And some routings combined with network coding have been proposed for wireless multi-hop network. In the routings combined with network coding, network coding condition is used to find network coding opportunities, which is very important to the performance improving of routings combined with network coding. However, the network coding conditions defined by existing routings combined with network coding unilaterally focus on the growth of network coding opportunities, which results in the increasing of cost and delay in routing discovery. Moreover, the more flows participating network coding, the higher probability of decoding failure, which degrade the network coding gain. In this paper, low complexity network coding condition (LCNC) is proposed. LCNC only detects two-flows network coding opportunity, and ensures the destination make successful decoding. In addition, the actual network coding gain is designed through analysis of link quality. Network coding opportunity will be ignored in case the actual network coding gain is negative. Based on LCNC, a low complexity network coding aware routing (LNCR) is designed aiming wireless multi-hop network. Simulation results demonstrate that LNCR obtain a balance between network coding gain and routing discovery cost, and can obtain higher network throughput when the network load is high compared with the classical network coding aware routings.

OBJECTIVE: To explore the effectiveness of Taylor spatial frame (TSF) in the treatment of tibiofibular fractures and computer-assisted closed reduction. METHODS: The clinical data of 30 cases of tibiofibular fractures with soft tissue injury treated with TSF between January 2015 and September 2017 was retrospectively analyzed. According to different reduction methods, the patients were divided into control group (15 cases, open reduction in TSF external fixation) and trial group (15 cases, closed reduction in 1-3 days after TSF external fixation). There was no significant difference in the general data such as gender, age, affected side, cause of injury, AO classification of fracture, time from injury to operation between the two groups (P>0.05). The operation time, intraoperative blood loss, fracture healing time, and removal time of external fixator were recorded and compared between the two groups. At 3 months after removal of external fixator, the limb function was evaluated according to Johner-Wruhs criteria for evaluating the final effect of tibial shaft fracture treatment. RESULTS: Both groups were followed up 9-16 months, with an average of 14 months. The operation time, intraoperative blood loss, fracture healing time, and removal time of external fixator in the trial group were significantly shorter than those in the control group (P

The SCN1A gene with 1274 point mutations in the coding regions or genomic rearrangements is the most clinically relevant epilepsy gene. Recent studies have demonstrated that variations in the noncoding regions are potentially associated with epilepsies, but no distinct mutation has been reported. We sequenced the 5′ upstream region of SCN1A in 166 patients with epilepsy and febrile seizures who were negative for point mutations in the coding regions or genomic rearrangements. A heterozygous mutation h1u-1962 T > G was identified in a patient with partial epilepsy and febrile seizures, which was aggravated by oxcarbazepine. This mutation was transmitted from the patient’s asymptomatic mother and not found in the 110 normal controls. h1u-1962 T > G was located upstream the most frequently used noncoding exon and within the promoter sequences. Further experiments showed that this mutation decreased the promoter activity by 42.1 % compared with that of the paired haplotype (P

To strengthen the prevention of cracks in hydration heat engineering. On the basis of summarizing and analyzing the models for hydration heat of concrete, numerical methods are used to calculate the temperature change curve of the core concrete in cement hydration stage. The thermal performance parameters of steel tubes and concrete are the essential basic data, which serves as a basis for research. Sectional dimension largely influences the shrinkage distortion of the core concrete in the concrete-filled steel tubes, which increases as the dimensions of the cross-section expand.

Many network applications, e.g., industrial control, demand Ultra-Low Latency (ULL). However, traditional packet networks can only reduce the end-to-end latencies to the order of tens of milliseconds. The IEEE 802.1 Time Sensitive Networking (TSN) standard and related research studies have sought to provide link layer support for ULL networking, while the emerging IETF Deterministic Networking (DetNet) standards seek to provide the complementary network layer ULL support. This article provides an up-to-date comprehensive survey of the IEEE TSN and IETF DetNet standards and the related research studies. The survey of these standards and research studies is organized according to the main categories of flow concept, flow synchronization, flow management, flow control, and flow integrity. ULL networking mechanisms play a critical role in the emerging fifth generation (5G) network access chain from wireless devices via access, backhaul, and core networks. We survey the studies that specifically target the support of ULL in 5G networks, with the main categories of fronthaul, backhaul, and network management. Throughout, we identify the pitfalls and limitations of the existing standards and research studies. This survey can thus serve as a basis for the development of standards enhancements and future ULL research studies that address the identified pitfalls and limitations.

The growth of network coding opportunitiesis considered the unique optimization goal by mostcurrent network coding based routing algorithms for wirelessmesh networks. This usually results in flows aggregationproblem in areas with coding opportunities, and degradesthe network performance. This paper proposes aLoad balanced coding aware multipath routing (LCMR)for wireless mesh networks. To facilitate the evaluation ofdiscovered multiple paths and the tradeoffs between codingopportunity and load balancing, a novel routing metric,Load balanced coding aware routing metric (LCRM) ispresented, which considers the load degree of nodes whendetects coding opportunities. LCMR could spread trafficover multipath to further balance load. Simulation results demonstrate that LCMR could evenly spread the traffic over the network with increasing network throughput in a heavy load at the expense of some coding opportunities.

This paper proposes a network coding aware QoS (quality of service) routing (NCQR) for wireless sensor network, which exploits network coding technology to improve the QoS routing of wireless sensor network. Network coding condition with QoS constraint is proposed, which provides proof for coding opportunity detection. To facilitate the evaluation of discovered routes, a novel routing metric, called CQRM (coding aware QoS routing metric), is presented, which jointly considers link quality, node congestion and coding opportunity. Simulation results demonstrate that NCQR decreases the blocking ratio of QoS requests significantly and prolongs network lifetime. Index Terms—Wireless sensor network; QoS; routing algorithm; network coding aware

Higher energy level and more compact structure are the trend of centrifugal compressor, which may lead to the rotordynamics instability problems and high vibration. These problems restrict the improvement of the the rotating machinery operation efficiency and bring about potential safety problems, especially, such as the subsynchronous vibration and unbalance vibration. Aiming at the potential instability caused by the excitation of the seal, a seal combined with electromagnetic damping function was designed in “Investigation on the seal structure design and rotor vibration controller for back-to-back centrifugal compressor (GT2016-56900)”. Here, the capability of the Active Magnetic Bearing (AMB)-Hole Pattern Seal (HPS) is investigated in the aspect of function and load characteristic. Furthermore, the electromagnetic damping seal actuator also has the potential to implement the unbalance control. In the aspect of control theory, we combined the damping control algorithm, which is used to control the rotor instability vibration, with the self-optimizing control algorithm for fundamental vibration control of rotor bearing system. The independently optimized control strategy was chosen according to the different frequency vibration waveform. Moreover, we built a comprehensive vibration control experiment platform that is mainly combined with the rotor, tilting pad bearings and electromagnetic damping seal actuator. We did experiment on simulating the instability condition, the control of the instable low frequency vibration, and the control of fundamental frequency vibration. The experimental results show that with the control hardware of high speed FPGA module and the self-optimizing control algorithm, the electromagnetic damping sealing can not only solve the instability caused by the original seal of centrifugal compressor to improve the system stability, but also be used as the active actuator to effectively control the vibration of the rotor system. At the same time, it is also found in the experiment that how to effectively restrain the influence of irrelevant noise and the reasonable selection of initial control parameters have a very important influence on the overall control effect, which is the urgent problem to be solved in the following work. This paper also provides a new design idea and a set of feasible active vibration control strategies for the high speed centrifugal compressor and has guiding significance for solving the problem of multi-frequency vibration and rotor stability of high speed centrifugal compressor.

Blade tip clearance (BTC) measurement and active clearance control (ACC) have been and continue to be a fundamental concern in turbomachinery, which are closely bound up with the efficiency and reliability. This paper addresses the BTC measurement and ACC experimental study based on eddy current pulse-trigger method (ECPTM). And the implementation of ACC by axial displacement of the blisk is novel and this paper is the first to present the technique. The purpose of this paper is three fold. The first portion of this paper addresses the BTC measurement in different rotating speeds based on the larger scale rig, where a high-bandwidth (100 kHz) eddy current sensor (HECS) is employed. The results show that the relative errors of BTC values are not much bigger than 20%. The result indicates that ECPTM is more generally applicable in the condition where the eddy current sensor (ECS) is insufficient sampling caused by the limit of narrow bandwidth, especially under the high linear velocity condition. The second portion of this paper describes the ACC system where an electro-hydraulic proportional position control system (EHPPCS) is employed as the actuator. EHPPCS has the advantages of small size, fast response, resistance to load stiffness, large output and simple operation, which is widely applicable to the automatic control system of industrial power. This system optimizes the geometry shapes of casing and the blade tips to create a linear relationship of BTC values related to the axial displacement of the rotor. The BTC values can be transferred into axial displacement of the rotor, and then a voltage/current-BTC values characteristic can be obtained by employing EHPPCS in different rotating speeds. Unfortunately, one of the core components of EHPPCS is an overflow valve with a non-linear and time-variable voltage/current-pressure characteristic. Besides, the pressure-axial displacement characteristic of tilting pad thrust bearing is also non-linear. All those non-linear characteristics make it unsatisfactory to use the conventional PID control algorithm to achieve effective control of the system, which cause many difficulties in controlling of axial displacement of the rotor. So the last portion of this paper is the experimental study on ACC based on the above system by adopting sliding mode adaptive control of nonlinear system (SMACNS). The BTC values have been obtained under different outlet pressures by changing the current in different rotating speeds. The results indicate that this approach has nice robustness and smooth controlled quantity, and can overcome the difficulty caused by nonlinearity, parameter uncertainty and load disturbance. And then, the precision verification and error analysis are made. However, this work is a proof-of-concept demonstration using a laboratory setup providing the basis for BTC active control and blade health monitoring (BHM) based on ECS.

Seed development includes an early stage of endosperm proliferation and a late stage of embryo growth at the expense of the endosperm in Arabidopsis thaliana. Abscisic acid (ABA) has known functions during late seed development, but its roles in early seed development remain elusive. In this study, we report that ABA-deficient mutants produced seeds with increased size, mass, and embryo cell number but delayed endosperm cellularization. ABSCISIC ACID DEFICIENT2 (ABA2) encodes a unique short-chain dehydrogenase/reductase that functions in ABA biosynthesis, and its expression pattern overlaps that of SHORT HYPOCOTYL UNDER BLUE1 (SHB1) during seed development. SHB1 RNA accumulation was significantly upregulated in the aba2-1 mutant and was downregulated by the application of exogenous ABA. Furthermore, RNA accumulation of the basic/region leucine zipper transcription factor ABSCISIC ACID-INSENSITIVE5 (ABI5), involved in ABA signaling, was decreased in aba2-1. Consistent with this, seed size was also increased in abi5. We further show that ABI5 directly binds to two discrete regions in the SHB1 promoter. Our results suggest that ABA negatively regulates SHB1 expression, at least in part, through the action of its downstream signaling component ABI5. Our findings provide insights into the molecular mechanisms by which ABA regulates early seed development.

There exist essential requirements for providing service differentiation in the next-generation networks. In this paper, AMSR (Agent-based Multi-Service Routing) is proposed and evaluated for Polar-orbit LEO broadband satellite networks. AMSR forwards best-effort traffic in a distribute manner using three factors: unfair traffic distribution, link utilization level and constellation geometry characteristics. Meanwhile, AMSR employs an on-demand source routing method, called agent-based inter-satellite link QoS routing (AIQR), to implement QoS routing in space. In AIQR, agent migrates based on best-effort forwarding to gather QoS routing information, and determines QoS path considering both call duration and the periodic changes in network topology. Moreover, with protecting ongoing communication in mind, a gradual rerouting strategy is introduced to deal with user-to-satellite and satellite-to-satellite handover. Through simulations on an Iridium-like system, AMSR is shown to achieve better QoS guarantee and more effective service differentiation as well as lower overhead compared with the previously proposed methods. Especially, simulation results thoroughly reveal AMSR's handover performance in terms of latency and hop count, rerouting frequency and overhead. Additionally, the credits and further research of this study are pointed out.

Network coding–based routing has been widely considered as a promising technology to improve the network throughput of wireless multihop network. However, existing network coding aware routings have the problem of failure decoding and usually neglect the transmission scheduling, which degrades the gain of network coding. In this article, a common network coding condition and traffic matching supported network coding aware routing is proposed for wireless multihop network. In this, common network coding condition is proposed to avoid the problem of failed decoding. In addition, traffic matching mechanism is presented to promote the occurrence of network coding. Besides, a coding and load aware routing metric, which jointly considers the network coding opportunity and node load, is designed to evaluate the discovered paths. Extensive simulations on NS2 demonstrate that CTNR increases the number of coding opportunities and network coding occurrence, and improves network throughput.

A novel distributed PZT control strategy based on characteristic model is presented for space frame structure in this paper. It is a challenge to obtain the exact mechanical model for space structure, since it is a coupling MIMO plant with unknown parameters and disturbances. Thus the characteristic modeling theory is adopted to establish the needed model, which can accurately describe the dynamic characteristics of the space frame structure in real time. On basis of this model, a keep tracking controller is designed to suppress the vibration actively. It is shown that the proposed model-free method is very robust and easy to implement. To solve the complex and difficulty problem on PZT location optimization, an efficient method with modal strain energy and maximum vibration amplitude is proposed. Finally, a simulation study is conducted to investigate the effectiveness of the proposed active vibration control scheme.

Network coding has been confirmed as a potential technology to improve performance of wireless mesh networks (WMNs) and a few network coding aware routings have been proposed. However, these mechanisms detect coding opportunities through local traffic pattern checking, which hardly obtains optimal routes. This paper proposes a Genetic algorithm based Coding Aware Routing (GCAR) for wireless mesh networks, which employs genetic algorithm to optimize routes and coding opportunities. In addition, the key ingredients in GCAR, e.g., chromosome representation, genetic operation of crossover and mutation, fitness function considering coding opportunity and interference, are carefully designed. Through simulations on a randomly generated wireless mesh network, GCAR is shown to find optimal routes within a short time, and achieve more improvements than the previously proposed methods on route setup time, throughput and load balancing.

Network coding has been widely acknowledged as an effective approach to improve the throughput of wireless mesh networks (WMNs) and a few network coding based routing algorithms for wireless mesh networks have been proposed. This paper investigates the state of the art of network coding based routing algorithms for WMNs that exploits network coding in routing algorithms. In addition, the taxonomy of network coding based routing for WMNs is presented and the typical network coding based routing algorithms for WMNs are reviewed by analyzing their specific characteristics, advantages and drawbacks. Some open problems in designing network coding based routing for wireless mesh networks are discussed finally.

Now in China, the management of construction waste still gets less attention than it deserves. The construction waste has caused huge consumption of limited resources and led to serious environment pollution. Consequently; it makes bad effect on China's sustainable development. Firstly, the definition of construction waste is provided in the paper. Then based on the analysis of the present management situation of construction waste, different of management modes of construction waste are evaluated, and then the mode of reducing construction waste from its source is presented, which would performs well to realize the reduction and recycling of construction waste. At the same time, this paper also puts forward the construction model of carrying out corresponding countermeasures; finally, the development trend of construction model in the future is prospected.

Polymers have been proved to have attractive mechanical characteristics, which made it desirable to choose these materials over traditional materials for numerous types of applications. As the uses of polymers increase, a thorough understanding of the mechanical behavior of these materials becomes vital in order to perform innovative and economical designs of various components. The main objective of this paper is to develop an effective method with the use of the Laplace inverse transform to describe the time dependent mechanical response of viscoelastic polymers. This general methodology is based on differential constitutive relations for viscoelastic polymers, avoiding the use of relaxation integral functions. As its application, the creep and relaxation properties of the materials are exhibited in the numerical examples.

The two limit equilibrium methods of bulk material (Variation method and wedge model method) is employed to analyze models of sliding cuneiform volume of bulk solid, the lateral pressure formula for squat silos and equations of failure plane about sliding cuneiform volume are obtained. Variations of the positions of failure plane with height/diameter ratio are analized on the basis of the analysis for positions of failure plane by solution of these equation. The applied range and calculation method of the formula, and pressure distribution are discussed. The effects of friction between bulk solid and squat silos on the positions of failure plane and lateral pressure of bulk solid are discussed. The conclusion is that caculation results is available for squat silo design when the friction takes no into account, and the applied range of the formula is that height/diameter ratio equals 1.3. It is widely appicable for almost all squat silos. The caculation results agree with that of the full-sized silo experiment. This is a reasonable calculation method for design of squat silo.

H9N2 subtype influenza virus has become worldwide and prevalent in China. Previous studies illustrated that at least three sublineages had been established in terrestrial poultry of Eurasian avian. In this presentation, eight full-length genes of an H9N2 strain, A/Chicken/Shanghai/F/98 (Ck/SH/F/98) were obtained. Sequence analysis and phylogenetic studies were conducted by comparing eight genes with those of all the available H9N2 strains from the GenBank. The results showed that four genes (HA, NA, M and NS genes) of Ck/SH/F/98 were incorporated into the sublineage represented by the early mainland China strain, Ck/BJ/1/94. However, the other four of RNP genes of Ck/SH/F/98 did not show close relationship with those of the three known sublineages' viruses. Therefore, Ck/SH/F/98 was a natural reassortant between different sublineages. In addition, comparison showed that Ck/SH/F/98 could be a putative precursor of a later isolate from southern China, Dk/ST/1605/01, with at least six genes of both closely related, indicating genes of Ck/SH/F/98 and early isolates had ever been circulating. Further comparison in terms of molecular markers of species specificity of HA1 revealed that DK/ST/1605/01 also resembled Ck/SH/F/98 more than a common earlier duck strain. The results supported the idea of two-way transmission between terrestrial and aquatic birds that emphasized the importance to raise concerns on the natural evolution of all the eight genes of H9N2 avian influenza viruses.

As the process of traditional dynamics modeling for rigid-flexible couple system is complex, this paper introduces the theory of characteristic modeling to simplify the modeling process. Unlike other reduced-order models, characteristic model compresses the high-order information into the characteristic parameters. Therefore, it will not lose model information. In addition, in order to improve the dynamic performance of flexible hub-beam system, a new reaching law of sliding mode control is proposed. The method of commbining sliding mode control and characteristic model is characteristic model-based adaptive dicrete-time sliding mode control(CMADSMC). Experimental results indicate that the designed DSMC can fast track the angle and the vibration of flexible beam will be quickly suppressed.

The stress-intensity factor (SIF) of the semi-elliptical surface crack in the finite body under extensional stress is sclculated by using the FEM software ANSYS release 5.5. The correction factor M f of SIF at different point along the front of the crack is determined. The relation between M f and the semi-elliptical shape a/c, the relative crack depth a/b, the variation of angle ϑ, the relative crack width 2c/w and the relative height-width ratio h/w are calculated respectively. Finally the application range and the modification of the engineering formula about SIF is proposed.

An RF photocathode gun which, along with a compact linac, forms the injection system for a planned FIR FEL amplifier experiment, has been commissioned in the high power radiation laboratory. This high-gradient gun has emitted 60 ps, 10 A electron beams of up to 3 MeV energy. These beams have been characterized by a variety of diagnostics. The quantum efficiency of Cs2Te has been measured at normal incidence. The energy and energy spread of the beam were tested using a dipole spectrometer, while the time structure was examined with a picosecond resolution streak camera. The emittance of the beam was measured using the pepper pot technique and its dependence on space charge and RF phase were found. The impact of these results on improving the design and operation of this high brightness photoinjector is discussed. This injector will be applied to the FIR FEL project in future.

This paper proposes a novel multicast routing for wireless sensor network, named Network Coding based Energy Efficient Multicast Routing (NEMR), which exploits intra-flow network coding within multicast session to improve the multicast reliability, and inter-flow network coding among multicast sessions to reduce the number of transmissions. Besides, network coding based retransmission mechanism and zero space based feedback mechanism are also presented. Extensive simulations on NS2 demonstrate that NEMR outperforms existing schemes in network lifetime and transmission efficiency, especially in case of heavy load.

This paper presents a simple multipath channel model to investigates the frequency correlation characteristics first, then analyzes the fading correlation coefficient between frequency difference Δf with the respect to transmission distance and radio carrier frequency. This work would provide a valuable reference for designing the wireless communication systems with high spectral efficiency and high tolerance to multipath fading.

Revision anterior cruciate ligament (ACL) surgery can be expected to become more common as the number of primary reconstruction keeps increasing. This study aims to investigate the factors causing instability after primary ACL reconstruction, which may provide an essential scientific base to prevent surgical failure.One hundred and ten revision ACL surgeries were performed at our institute between November 2001 and July 2012. There were 74 men and 36 women, and the mean age at the time of revision was 27.6 years (range 16 - 56 years). The factors leading to instability after primary ACL reconstruction were retrospectively reviewed.Fifty-one knees failed because of bone tunnel malposition, with too anterior femoral tunnels (20 knees), posterior wall blowout (1 knee), vertical femoral tunnels (7 knees), too posterior tibial tunnels (12 knees), and too anterior tibial tunnels (10 knees). There was another knee performed with open surgery, where the femoral tunnel was drilled through the medial condyle and the tibial tunnel was too anterior. Five knees were found with malposition of the fixation. One knee with allograft was suspected of rejection and a second surgery had been made to take out the graft. Three knees met recurrent instability after postoperative infection. The other factors included traumatic (48 knees) and unidentified (12 knees).Technical errors were the main factors leading to instability after primary ACL reconstructions, while attention should also be paid to the risk factors of re-injury and failure of graft incorporation.