Joint Active and Passive Beamforming Design for Hybrid RIS-Aided Integrated Sensing and Communication

Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink ISAC system that simultaneously serves multiple single-antenna communication users and senses multiple targets. Hybrid RIS differs from fully passive RIS in that it is composed of both active and passive elements, with the active elements having the effect of amplifying the signal in addition to phase-shifting. We maximize the achievable sum rate of communication users by collaboratively improving the beamforming matrix at the dual function base station(DFBS) and the phase-shifting matrix of the hybrid RIS, subject to the transmit power constraint at the DFBS, the signal-to-interference-plus-noise-ratio(SINR) constraint of the radar echo signal and the RIS constraint are satisfied at the same time. The builtin RIS-assisted ISAC design problem model is significantly non-convex due to the fractional objective function of this optimization problem and the coupling of the optimization variables in the objective function and constraints. As a result, we provide an effective alternating optimization approach based on fractional programming(FP) with block coordinate descent(BCD)to solve the optimization variables. Results from simulations show that the hybrid RIS-assisted ISAC system outperforms the other benchmark solutions.

Task-Oriented Topology System Synthesis of Reconfigurable Legged Mobile Lander Integrating Active and Passive Metamorphoses

To explore hostile extraterrestrial landforms and construct an engineering prototype,this paper presents the task-oriented topology system synthesis of reconfigurable legged mobile lander(ReLML)with three operation modes from adjusting,landing,to roving.Compared with our preceding works,the adjusting mode with three rotations(3R)provides a totally novel exploration approach to geometrically matching and securely arriving at complex terrains dangerous to visit currently;the landing mode is redefined by two rotations one translation(2R1T),identical with the tried-and-tested Apollo and Chang'E landers to enhance survivability via reasonable touchdown buffering motion;roving mode also utilizes 2R1T motion for good motion and force properties.The reconfigurable mechanism theory is first brought into synthesizing legged mobile lander integrating active and passive metamorphoses,composed of two types of metamorphic joints and metamorphic execution and transmission mechanisms.To reveal metamorphic principles with multiple finite motions,the finite screw theory is developed to present the procedure from unified mathematical representation,modes and source phase derivations,metamorphic joint and limb design,to final structure assembly.To identify the prototype topology,the 3D optimal selection matrix method is proposed considering three operation modes,five evaluation criteria,and two topological subsystems.Finally,simulation verifies the whole task implementation process to ensure the reasonability of design.

HPR1000： Advanced Pressurized Water Reactor with Active and Passive Safety

HPR1000 is an advanced nuclear power plant(NPP)with the significant feature of an active and passive safety design philosophy,developed by the China National Nuclear Corporation.On one hand,it is an evolutionary design based on proven technology of the existing pressurized water reactor NPP;on the other hand,it incorporates advanced design features including a 177-fuel-assembly core loaded with CF3 fuel assemblies,active and passive safety systems,comprehensive severe accident prevention and mitigation measures,enhanced protection against external events,and improved emergency response capability.Extensive verification experiments and tests have been performed for critical innovative improvements on passive systems,the reactor core,and the main equipment.The design of HPR1000fulfills the international utility requirements for advanced light water reactors and the latest nuclear safety requirements,and addresses the safety issues relevant to the Fukushima accident.Along with its outstanding safety and economy,HPR1000 provides an excellent and practicable solution for both domestic and international nuclear power markets.

Effects of active and passive training apparatus combined with rehabilitation training on lower limb function of stroke patients during recovery period

Stroke patients always spontaneously do some learning and training of motor functions; however, learning and training are not prompt and right, while patients do not have enough activity amounts. Active and passive motor training apparatus is aimed directly at lower limb training so as to stimulate nerve function through stimulating muscular movement. Based on motor mileage, motor time, various power supplies and velocity of active and passive training apparatus, we can understand the training condition and adjust training program. OBJECTIVE： To observe the effects of grade-III rehabilitation training combining with active and passive training apparatus on lower limb function, muscle strength and activity of daily living （ADL） in stroke patients during recovery period. DESIGN： Contrast observation. SETTING： Department of Rehabilitation, Jilin Academic Institute of Traditional Chinese Medicine. PARTICIPANTS： A total of 80 patients with stroke-induced hemiplegia after stabilizing vital signs for 2 weeks were selected from Department of Rehabilitation, Jilin Academic Institute of Traditional Chinese Medicine from January to June 2007. There were 47 males and 33 females, and their ages ranged from 41 to 75 years. All patients met the diagnostic criteria of the Fourth National Cerebrovascular Disease Academic Meeting in 1995 and were diagnosed as cerebral hemorrhage or cerebral infarction through CT or MRI examinations in clinic. Patients and their parents provided the confirmed consent. Based on therapeutic orders of hospitalization, patients were randomly divided into treatment group and control group with 40 patients in each group. METHODS： Patients in the control group received physical therapy and occupational therapy combining with rehabilitative treatment based on grade-III rehabilitative treatment program, which was set by the National Cerebrovascular Disease Topic Group. In addition, patients in the treatment group were trained with active and passive motor training apparatus based on therapeutic procedures in the control group. The active and passive motor training apparatus was designed as the therapeutic style of nervous system; otherwise, the treatment was performed once a day, 30 minutes once and 6 times per week. Four weeks were regarded as a course. MAIN OUTCOME MEASURES： Before treatment, at 2 weeks after treatment and after the first course, bare-handed muscle strength examination was used to check muscle strength and muscular tension; in addition, simple Fugl-Meyer assessment （FMA） and diagnostic criteria which were set by the Fourth National Cerebrovascular Disease Academic Meeting were used to evaluate motor function of limbs and total ADL. RESULTS： All 80 stroke patients were involved in the final analysis. ① Muscle strength of lower limbs was improved in both treatment group and control group. After the first course, muscle strength in the treatment group was obviously superior to that in the control group （ x^2=6.64, P 〈 0.05）. ② After the first course, Fugl-Meyer scores in the treatment group were higher than those in the control group, and there was significant difference （t =2.82, P 〈 0.05）. ③ Muscular tension of lower limbs was not changed in both treatment group and control group after treatment （P 〉 0.05）. ④ After the first course, ADL in the treatment group was superior to that in the control group （P 〈 0.05）. Among patients in the treatment group, 24 cases （60%） had obvious progress, 16 （40%） had progress, and 0 （0%） did not have any changes. On the other hand, among patients in the control group, 13 cases （32.5%） had obvious progress, 26 （65%） had progress, and 1 （2.5%） did not have any changes. CONCLUSION： Rehabilitation training combining with active and passive motor training apparatus can promote the recovery of lower limb disorder, increase muscle strength, control spasm, improve ADL and cause satisfactorily clinical effects in stroke patients during recovery period.

Design of novel RGO/2D strip-like ZIF-8/DMAOP ternary hybrid structure towards high-efficiency microwave absorption, active and passive anti-corrosion, and synergistic antibacterial performance

In order to meet the requirements of the marine environment for microwave absorption(MA)materials,we put forward the strategy of constructing multi-functional composite materials,which integrate microwave absorption,anti-corrosion,and antibacterial properties.Herein,graphene oxide(GO)was used as a template to induce the growth of zeolitic imidazolate framework-8(ZIF-8),simultaneously as a two-dimensional(2D)nanocontainers to load corrosion inhibitors to achieve pH-responsive and self-healing properties.Finally,quaternary ammonium salt(dimethyl octadecyl(3-trimethoxylsilyl propyl)ammonium chloride(DMAOP))and sodium ascorbate(VCNa)were introduced to achieve synergistic antibacterial activity and the reduction of GO.The 2D strip-like structure of ZIF-8 was due to the confined growth induced by the electrostatic attraction between ZIF-8 and GO sheets.The as-obtained reduced GO(RGO)/ZIF-8/DMAOP5 exhibited excellent microwave absorption(MA)properties,with a minimum reflection loss(RL)value of-47.08 dB at 12.73 GHz when the thickness was 2.8 mm.Moreover,the effective absorption bandwidth reached 6.84 GHz.After soaking in 3.5%NaCl solution for 35 days,the RGO/ZIF-8/DMAOP5-0.7%coating still achieved an impedance value of 4.585×107Ω·cm^(2) and a protective efficiency of 99.994%,providing superior anti-corrosion properties.In addition,fantastic antibacterial activity was obtained,with the antibacterial rates of RGO/ZIF-8/DMAOP_(10) reaching 99.39%and 100%against Escherichia coli and Staphylococcus aureus.This work could open new avenues towards the development of a new generation of multifunctional MA materials.

Influence of active and passive equipment for advanced pressurized water reactor on thermal hydraulic and source term behavior in severe accidents

Extensive studies have been carried out on the behavior of core degradation and fission products of common pressurized water reactors(PWRs).However,few of them have investigated the relationship between thermal hydraulic and fission product behavior in advanced passive PWRs.Due to the impact of thermal hydraulic be-haviors in different accident sequences on the release and transportation of fission products,an integrated severe accident analysis(ISAA)code with highly coupled thermal hydraulic and source term calculations is required to simultaneously analyze thermal hydraulic and source term behavior.For advanced passive PWRs,important safety systems that may affect the behavior of the core and fission products should be considered.It is therefore necessary to simulate the thermal hydraulic and fission product behavior of advanced passive PWRs.In this study,the ISAA code is adopted to simulate the occurrence of a hypothetical double ended cold leg LBLOCA of HPR1000 in three scenarios of equipment failure.The results show that the high-temperature fuel rods and cladding ma-terials exhibit delayed failure at the lower position of the active core,whereas earlier failure at higher position during the reflooding.Active and passive equipment affects fuel temperature,the oxidation conditions of the fuel,the interaction of fission products and structural materials,and the state of the fuel,thereby affecting the release of fission products in the fuel.HPR1000 only relies on passive equipment to relieve the core degradation in severe accidents,realize the in-vessel retention of melt,and eliminate the ex-vessel release possibility of fission product.It is hoped that the results can provide references for HPR1000 to formulate the severe accident management guidelines(SAMG).

Active and passive compliant force control of ultrasonic surface rolling process on a curved surface

Ultrasonic surface rolling process(USRP)is one of the effective mechanical surface enhancement techniques.During the USRP,unstable static force will easily do harm to the surface quality.In order to achieve a higher surface quality on the part with a curved surface,an active and passive compliant USRP system has been developed.The compliant USRP tool can produce the natural obedience deformation along the part surface.Force control based on the fuzzy Proportional-integral-derivative(PID)method is then designed to maintain the static force during the USRP.Experiments have been performed on a real aero-engine blade with curved surface.It is proved that the deigned active and passive compliant USRP system can significantly reduce the force variation from 42.2 N to 4.2 N,and achieve a uniform surface quality after processing.

Countermeasure Method for Stope Instability in Crown Pillar Area of Cut and Fill Underground Mine

Maintaining stability as well as optimizing recovery of crown pillar, a pillar separating surface area with the uppermost stope in overhand cut and fill underground mining method, is important. Failures in stope may lead to crown pillar failures and cause surface subsidence. Increasing crown pillar thickness will increase crown pillar stability yet reduce mining recovery because part of crown pillar is formed by ore body. Preventing stope failure is the key to maintain stability and optimize recovery of crown pillar. Therefore, it is important to study countermeasure method for stope failure especially in crown pillar area. An attempt has been made to investigate the effectiveness of various countermeasures for stope failure in crown pillar area by means of parametric study. The result shows active type support system is effective for supporting stope in high vertical stress condition while the passive one needs to be installed if the stope is opened in high horizontal stress condition. In general, more supporting capacity from both type support systems is needed if the stope is opened in more severe geological condition. Another countermeasures, sill pillar and surface pile, are introduced for stope instability in crown pillar and non-crown pillar area. Sill pillar is an abandoned slice of unstable stope based on stability analysis. Sill pillar is very effective to stabilize stope both in crown pillar and non-crown pillar area, especially for stope in high horizontal stress condition. Sill pillar application in model with stress ratio 2 can optimize 20 meter thickness of crown pillar into 5 meter. Another proposed countermeasure is surface pile. Surface pile can be installed from the surface to improve stability of crown pillar and stope. The most effective use of surface pile is found in simulation of model with stress ratio 0.75 where surface pile can optimize 15 meter thickness of crown pillar into 5 meter.

Remarks on Definitions of Perturbation in General Relativity

There are two kinds of definitions of perturbation of physical quantities in the framework of general relativity： one is direct, the other is geometrical. Correspondingly, there are two types of gauge transformation related with these two definitions. The passive approach is based on the property of general covariance, and the active one is through the action of Lie-derivative. Although under a proper coordinate choice, the two approaches seem to agree with each other, they are different in nature. The geometrical definition of relativistic perturbation and the active approach for gauge transformation are more rigorous in mathematics and less confusing in physical explanation. The direct definition, however, seems to be plagued with difficulties in physical meaning, and the passive approach is more awkward to use, especially for high-order gauge transformations.

A+P一体化5G设备的使用探讨

随着5G时代的到来,各地5G基站的建设如火如荼,同时5G网络建设存在工程投资大、5G天线部署需要关注覆盖性能及部署周期等问题。文章针对在利旧基站建设过程中存在的天面空间受限、5G低挂高、铁塔风荷载受限等问题,对A+P(Combination of active and passive antennas)一体化设备在中国电信和中国联通的5G基站建设中的使用方式提出一些建议,根据A+P设备在不同建设场景来进行工程建设、投资分析,说明A+P一体化设备的较高实用性。

Estimation of vehicle states and tire-road friction using parallel extended Kalman filtering

A model-based estimator design and implementation is described in this paper to undertake combined estimation of vehicle states and tire-road friction coefficients.The estimator is designed based on a vehicle model with three degrees of freedom(3-DOF) and the dual extended Kalman filter(DEKF) technique is employed.Effectiveness of the estimation is examined and validated by comparing the outputs of the estimator with the responses of the vehicle model in CarSim in three typical road adhesion conditions(high-friction,low-friction,and joint-friction roads).Simulation results demonstrate that the DEKF estimator algorithm designed is able to obtain vehicle states(e.g.,yaw rate and roll angle) as well as road friction coefficients with reasonable accuracy.

闪电河流域农牧交错带微波遥感土壤水分产品评价

空间网格分辨率为9 km的SMAP(Soil Moisture Active and Passive)、0.1D(Degree)的ASCAT(The Advanced Scatterometer)、25 km的FY-3B以及25 km ESA-CCI(European Space Agency-Climate Change Initiative)是较为广泛应用的卫星遥感土壤水分产品,对数据质量的评价是进一步应用于旱情监测、蒸散发估算等研究的前提。本研究基于2018年9月在闪电河流域内蒙古农牧交错带区域开展的碳、水循环与能量平衡遥感综合试验,采用近似同步的两种尺度观测数据即点尺度地面实测土壤水分数据以及面尺度(1 km×1 km)机载土壤水分数据,利用RMSE(Root Mean Square Error),MAE(Mean Absolute Error),R(Correlation Coefficient),Bias以及ubRMSE(unbiased Root Mean Square Error)等评价指标分别对SMAP,ASCAT,FY-3B,ESA-CCI土壤水分卫星遥感产品进行了评价。本研究利用机载土壤水分数据作为桥梁,实现了从点尺度地面实测土壤水分数据、至面尺度(1 km×1 km)机载土壤水分数据、再至粗格网面尺度(9 km×9 km、0.1 D×0.1 D、25 km×25 km)卫星遥感土壤水分产品的对比分析过程。利用地面观测值对机载观测土壤水分开展评价分析,发现在裸土区域,机载土壤水分数据与地面实测数据较为一致,RMSE,MAE,Bias,ubRMSE以及R值分别为0.033 cm^(3)/cm^(3),0.030 cm^(3)/cm^(3),-0.004 cm^(3)/cm^(3),0.033 cm^(3)/cm^(3),0.474。对卫星土壤水分产品的评价结果显示,SMAP的9 km土壤水分卫星产品与地面观测更为一致,其RMSE,MAE,Bias,ubRMSE以及R值分别为0.037 cm^(3)/cm^(3),0.032 cm^(3)/cm^(3),-0.008 cm^(3)/cm^(3),0.036 cm^(3)/cm^(3),0.507。SMAP,ASCAT,FY-3B以及ESA-CCI与机载土壤水分数据有更高的相关性,R值分别为0.735,0.558,0.558,0.575。综上,闪电河流域实验区内的4种卫星遥感土壤水分产品中,SMAP产品与地面土壤水分、机载土壤水分数据均较为一致,其次是FY-3B与ESA-CCI。

A novel cleanliness control method for disk amplifiers

As the key part for energy amplification of high-power laser systems,disk amplifiers must work in an extremely clean environment.Different from the traditional cleanliness control scheme of active intake and passive exhaust(AIPE),a new method of active exhaust and passive intake(AEPI)is proposed in this paper.Combined with computational fluid dynamics(CFD)technology,through the optimization design of the sizes,shapes,and locations of different outlets and inlets,the turbulence that is unfavorable to cleanliness control is effectively avoided in the disk amplifier cavity during the process of AEPI.Finally,the cleanliness control of the cavity of the disk amplifier can be realized just by once exhaust.Meanwhile,the micro negative pressure environment in the amplifier cavity produced during the exhaust process reduces the requirement for sealing.This method is simple,time saving,gas saving,efficient,and safe.It is also suitable for the cleanliness control of similar amplifiers.