Dynamic Spectrum Control-Assisted Secure and Efficient Transmission Scheme in Heterogeneous Cellular Networks

Heterogeneous cellular networks(HCNs)are envisioned as a promising architecture to provide seamless wireless coverage and increase network capacity.However,the densified multi-tier network architecture introduces excessive intra-and cross-tier interference and makes HCNs vulnerable to eavesdropping attacks.In this article,a dynamic spectrum control(DSC)-assisted transmission scheme is proposed for HCNs to strengthen network security and increase the network capacity.Specifically,the proposed DSC-assisted transmission scheme leverages the idea of block cryptography to generate sequence families,which represent the transmission decisions,by performing iterative and orthogonal sequence transformations.Based on the sequence families,multiple users can dynamically occupy different frequency slots for data transmission simultaneously.In addition,the collision probability of the data transmission is analyzed,which results in closed-form expressions of the reliable transmission probability and the secrecy probability.Then,the upper and lower bounds of network capacity are further derived with given requirements on the reliable and secure transmission probabilities.Simulation results demonstrate that the proposed DSC-assisted scheme can outperform the benchmark scheme in terms of security performance.Finally,the impacts of key factors in the proposed DSC-assisted scheme on the network capacity and security are evaluated and discussed.

Improving the Transmission Efficiency of a WSN with the IACO Algorithm

The goal of this study is to reduce the energy consumption of the sensing network and enhance the overall life cycle of the network.This study proposes a data fusion algorithm for wireless sensor networks based on improved ant colony optimization(IACO)to reduce the amount of data transmitted by wireless sensor networks(WSN).This study updates pheromones for multiple optimal routes to improve the global optimal route in search function.The algorithm proposed in this study can reduce node energy consumption,improve network load balancing and prolong network life cycle.Through data fusion,regression analysis model and information processing of each node,this study uses an improved ant colony algorithm to identify the transferals avoid superfluous energy waste caused by long-span network transferal,set the shortest route and transmit data to the central node.The algorithm proposed in this study is conducive to improving the life cycle and stable network,that is,the most suitable and effective way to improve the energy consumption rate of the sensing nodes.

The Efficiency of Southern rice black-streaked dwarf virus Transmission by the Vector Sogatella furcifera to Different Host Plant Species

Southern rice black-streaked dwarf disease is a new rice disease that severely affects rice production in South China.To understand transmission capacity of the vector Sogatella furcifera to Southern rice black-streaked dwarf virus（SRBSDV） among different host plant species,potential host plants of SRBSDV collected from the diseased rice field and/or adjacent to the field in Hunan Province,China,were determined by RT-PCR,and the transmission rates of SRBSDV by S.furcifera among different host plant species were investigated.The results showed that host plants of SRBSDV in the rice fields were five of family Gramineae（Oryza sativa,Echinochloa crusgalli,Zea mays,Paspalum distichum,Alopecurus aequali） and two of family Cyperaceae（Juncellus serotinus and Cyperus difformis）.S.furcifera could not transmit SRBSDV between gramineous plants and cyperaceous plants,and could not transmit SRBSDV between the gramineous plants,J.serotinus and C.difformis as well.However,SRBSDV could be transmitted by S.furcifera within gramineous plants.S.furcifera could transmit SRBSDV between interspecies among three species plants（O.sativa,E.crusgalli and Z.mays）,and between P.distichum and A.aequali.At 15,20,25,30,and 35°C,both macropterous and brachypterous adult of S.furcifera could transmit SRBSDV from the plants（e.g.,E.crusgalli,Z.mays and O.sativa） infected with SRBSDV to rice seedlings.The transmission rates were first increased and then decreased with the increase of temperature.Macropterous adults transmitted SRBSDV from the viruliferous E.crusgalli,Z.may and rice plants to the healthy rice seedlings,and the infected rates of rice seedlings were 26.2,18.8 and 23.7% at 15°C,56.6,64.6 and 53.6% at 25°C,and was 11.2,10.2 and 7.3% at 35°C,respectively.Transmission capacity of brachypterous adults was significantly higher than that of macropterous adults at 15,20 and 25°C（P0.05）,while transmission capacity of brachypterous adults was relatively lower compared with that of macropterous ones at 35°C.These results offer evidence on the transmission of SRBSDV via the vector S.furcifer among different host plants,which can be helpful to control Southern rice black-streaked dwarf disease by the appropriate cultural measures in South China.

Research and Design of Hydro-mechanical Continuously Variable Transmission for Tractors

A new type continuous variable transmission device, a hydro-mechanical continuously variable transmission （HMCVT） for agricultural tractors is developed, which is composed of a single planetary gear differential train, a hydraulic transmission system consisted of variable displacement pump and fixed displacement motor and a multi-gear fixed step radio transmission. Based on the analysis of types of hydrostatic mechanical transmission （HMT） and styles of hydraulic transmission, the general drive scheme for HMCVT is obtained. The method of selecting mechanical parameters and hydraulic units is explained, and the stepless speed regulation characteristic of HMCVT is analyzed. This paper also specializes the calculating method of transmission efficiency. It shows that tractors assembled with HMCVT can obtain a continuously variable speed and achieve high drive efficiency.

Optimization Transmission Efficiency with Driver Intention for Automotive Continuously Variable Transmission under Slip Mode

This study proposes and experimentally validates an optimal integrated system to control the automotive continuously variable transmission(CVT)by Model Predictive Control(MPC)to achieve its expected transmission efficiency range.The control system framework consists of top and bottom layers.In the top layer,a driving intention recognition system is designed on the basis of fuzzy control strategy to determine the relationship between the driver intention and CVT target ratio at the corresponding time.In the bottom layer,a new slip state dynamic equation is obtained considering slip characteristics and its related constraints,and a clamping force bench is established.Innovatively,a joint controller based on model predictive control(MPC)is designed taking internal combustion engine torque and slip between the metal belt and pulley as optimization dual targets.A cycle is attained by solving the optimization target to achieve optimum engine torque and the input slip in real-time.Moreover,the new controller provides good robustness.Finally,performance is tested by actual CVT vehicles.Results show that compared with traditional control,the proposed control improves vehicle transmission efficiency by approximately 9.12%-9.35%with high accuracy.

Effects of evacuation assistant's leading behavior on the evacuation efficiency: Information transmission approach

Evacuation assistants are expected to spread the escape route information and lead evacuees toward the exit as quickly as possible. Their leading behavior influences the evacuees＇ movement directly, which is confirmed to be a decisive factor of the evacuation efficiency. The transmission process of escape information and its function on the evacuees＇ movement are accurately presented by the proposed extended dynamic communication field model. For evacuation assistants and eevacuees, their sensitivity parameter of static floor field（SFF）, kL S, and kS, are fully discussed. The simulation results e indicate that the appropriate kL Sis associated with the maximum kSof evacuees. The optimal combinations of kL Sand e kSwere found to reach the highest evacuation efficiency. There also exists an optimal value for evacuation assistants＇ information transmission radius.

Simulation of x-ray transmission through an ellipsoidal capillary

This paper develops a simulation program for x-ray transmission in an ellipsoidal capillary based on a ray-tracing method. The influence of the parameters of ellipsoidal capillary and x-ray energy on transmission efficiency, full width at half maximum and power density gain of x-ray beams through an ellipsoidal capillary was analysed by this program. It shows that the particular rules of the ellipsoidai capillary x-ray lens are different from the polycapillary lens. Furthermore, this analysis method can be applied to the optimized design of ellipsoidal capillary.

Design and Test Analysis of a Solar Array Root Hinge Drive Assembly

A root hinge drive assembly is preferred in place of the classical viscous damper in a large solar array system.It has advantages including better deployment control and higher reliability.But the traditional single degree of freedom model should be improved.A multiple degrees of freedom dynamics model is presented for the solar arrays deployment to guide the drive assembly design.The established model includes the functions of the torsion springs,the synchronization mechanism and the lock-up impact.A numerical computation method is proposed to solve the dynamics coupling problem.Then considering the drive torque requirement calculated by the proposed model,a root hinge drive assembly is developed based on the reliability engineering design methods,and dual actuators are used as a redundancy design.Pseudo-efficiency is introduced and the major factors influencing the（pseudo-）efficiency of the gear mechanism designed with high reduction ratio are studied for further test data analysis.A ground prototype deployment test is conducted to verify the capacity of the drive assembly.The test device consists of a large-area solar array system and a root hinge drive assembly.The RHDA development time is about 43 s.The theoretical drive torque is compared with the test values which are obtained according to the current data and the reduction efficiency analysis,and the results show that the presented model and the calibration methods are proper enough.

Investigation of combined degrader for proton facility based on BDSIM/FLUKA Monte Carlo methods

The significant advantage of proton therapy over other particle-based techniques is in the unique physical characteristics of the Bragg peak.It can achieve a highly conformal dose distribution and maximize the probability of tumor control by varying the irradiation energy.Most proton facilities use cyclotrons for fixed energy beam extraction and are equipped with degrader and collimator systems for energy modulation and emittance suppression.However,interactions between charged particles and degrader materials inevitably cause beam loss and divergence and deteriorate beam performance,which present great challenges for downstream transport and clinical treatment.In this work,we investigate a method of energy reduction by combining boron carbide and graphite in a degrader to obtain greater beam transmission at lower energy.The results demonstrate that the beam size and emittance at the exit of the combined degrader diverge less than those of multi-wedge one in the energy range of 70-160 MeV.Correspondingly,the transmission efficiency after the first dipole also shows improvements of 36.26%at 70 MeV and 70.55%at 110 MeV.As a component with a high activity level,the degrader causes additional ambient radiation during operation.Residual induced radiation even remains several hours after system shutdown.Analysis of material activation and induced radiation based on 1 h irradiation with a 400 nA beam current shows that the combined degrader has a definite advantage in shielding despite producing more secondary particles.Both radioactivity and average ambient dose equivalent are reduced by 50%compared with the multiwedge degrader at the important cooling time of 1 h.After 12 h and 24 h of cooling,the radiation levels of degraders decrease slightly due to the presence of long half-life residual nuclides.The average dose generated from the multi-wedge degrader is still 1.25 times higher than that of the combined one.

Eavesdropping on the quantum dialogue protocol in lossy channel

We present an improved eavesdropping scheme on the quantum dialogue protocol in lossy channel, which is based on the strategies of Wojcik [Phys. Rev. Lett. 90 157901 （2003）] and ZML [Phys. Lett. A 333 46 （2004）] attack schemes. We show that our attack scheme doubles the domain of Eve＇s eavesdropping and Eve can gain more information of the communication with less risk of being detected. Finally, a possible improvement for the dialogue protocol security is proposed.

Electron transmission ef f iciency of gating-GEM foil for TPC

In a TPC, ion feedback from the readout detector can cause a space-charge effect and distort the electrical field in the drift region. Gating is one of the effective methods to solve this problem, which can block ions at the expense of losing a certain amount of primary electrons. Compared with the traditional design with a wire structure, gating based on GEM foil is more attractive because of its simplicity. In this paper, the factors influencing the electron transmission efficiency are studied with simulations and experiments. After optimizing all these parameters, an electron transmission efficiency over 80% is obtained.

Beam transmission efficiency of the HIRFL-SSC

In this paper we address the problem of the low beam transmission efficiency of the HIRFL-SSC. The influence of the SFC-SSC energy match, the SSC RF voltage, and harmonic field in the injection area of the SSC, and the SSC central trajectory on the beam transmission efficiency have been analyzed both from the theoretical side and from the actual operating data. The main reason is that the soft-edge approximation of the magnet field （the so-called theoretical field） and the simplified calculation programs were adopted when calculating the beam center trajectory and designing the injection and extraction system, and the measured magnetic field was not used to correct the calculation results. These led to large deviations of the calculated center trajectory, and then resulted in low efficiency of the SSC beam transmission. Therefore, the re-calculation of SSC beam center trajectory and injection and extraction system, as well as the measured magnet field correction are the key points required to solve the problem.

Analysis of Transmission Power and Efficiency of Side-Mounted Inductive Power Supply System for Metal Rotary Shafts

The online detection of metal shaft parameters,such as torque,power and deformation,is widely applied in engineering projects.The power supply of metal shafts is the key to the detection reliability and practicality.However,traditional slip ring and battery power supply are limited in reliability and service life.In this paper,a side-mounted inductive power supply system for the rotating metal shaft is designed by using a Utype core.The equivalent reluctance and circuit models of the system are analyzed,and the methods of improving the coupling coefficient and transmission efficiency are proposed from theoretical analysis.Through the finite element simulation analysis of the system,the general relationships between the transmission power and efficiency of the system and the number of coil turns,the working frequency and the load are analyzed.The accuracy of theoretical analysis and simulation analysis is verified by the practical power transmission experiments.This paper provides a novel and reliable power supply method for inductive power supply of rotating equipment,and enriches the solutions of rotating power supply.

Improved space-time processing for X channel using precoders

The article investigates how to send perfect space-time codes with low feedback amount and symbol-by-symbol decoding for X channel using precoders. It is assumed that two users are introduced with two antennas and two receivers. Each user employs a rate-2 space-time block code and follows certain rule when sending codewords. The multi-user interference is eliminated by pre-coding at the transmitter and linear processing at the receiver. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces feedback amount and improves the transmission efficiency, while keeping the same decoding complexity. Simulations demonstrate the validity of the proposed scheme.

Recalculation of the HIRFL-SSC injection and extraction system

In order to further improve beam transmission efficiency at the SSC, the beam center trajectory and injection and extraction system are recalculated based on the program group used in the final design of the GANIL accelerator, with some necessary changes and the addition of some auxiliary programs. The two different types of injection and extraction elements （the bending magnet and the inductive septum） are distinguished, and their interaction with the ambient field is considered. More focus is placed on considering the differences in the magnet field inhomogeneity of the ambient field in the located area of the inductive septum where the ends are situated in the ambient field （between the main magnet poles）. Thus the gradient magnetic field problem of the inductive septum is solved perfectly. As well as preparing the necessary auxiliary programs and taking the structural integration of the SSC magnetic field maps, the measured magnet field correction is completed. Therefore, the trajectory and a variety of injection and extraction system parameters are obtained. According to the recalculation results, the SSC beam transmission efficiency will be enhanced significantly.

Automotive Traction Drive Speed Reducer Efficiency Testing

The move from internal combustion engine vehicles to electric vehicles is happening rapidly,which demands a stepwise change in priorities for the vehicle design process with rational consideration of emerging technologies.This paper focuses on the efficiency of a particular form of high fixed-ratio(15:1)traction drive speed reducer.This is suitable for use in conjunction with a high-speed electric motor for automotive applications.A general discussion of the characteristics of other fixed-ratio traction drives is provided followed by an analysis of underlying efficiency issues.The paper presents details of the speed reducer prototype called a"Silk Drive"and the vehicle for which it was designed.Data from laboratory testing of the prototype are presented,and an efficiency map for the transmission is developed.The efficiency map and vehicle parameters are used in a simulation to determine the overall transmission efficiency for the world harmonized light vehicles test cycles(WLTC)class 3b drive cycle.The importance of transmission efficiency at low power levels,in specific input speed and torque regions,is demonstrated using a novel method for identifying those speed torque regions that most strongly affect overall efficiency.The method applies to all drivetrain components and pinpoints those regions that need to be the focus in the optimal design of such components.This paper presents evidence that the efficiency of zero-spin,fixed-ratio traction drives is similar to that of conventional gear drives.

On the Mathematical Nature of Wireless Broadcast Trees

Trees are arguably one of the most important data structures widely used in information theory and computing science. Different numbers of intermediate nodes in wireless broadcast trees may exert great impacts on the energy consumption of individual nodes, which are typically equipped with a limited power supply in a wireless sensor network; this limitation may eventually determine how long the given wireless sensor network can last. Thus, obtaining a deep understanding of the mathematical nature of wireless broadcast trees is of great importance. In this paper, we give new proof of Cayley＇s well-known theorem for counting labeled trees. A distinct feature of this proof is that we purely use combinatorial structures instead of constructing a bijection between two kinds of labeled trees, which is in contrast to all existing proofs. Another contribution of this work is the presentation of a new theorem on trees based on the number of intermediate nodes in the tree. To the best of our knowledge,this work is the first to present a tree enumeration theorem based on the number of intermediate nodes in the tree.