Optimization Study of Active-Passive Heating System Parameters in Village Houses in the Southern Xinjiang Province

Aiming at the problems of large energy consumption and serious pollution of winter heating existing in the rural buildings in Southern Xinjiang,a combined active-passive heating system was proposed,and the simulation software was used to optimize the parameters of the system,according to the parameters obtained from the optimization,a test platform was built and winter heating test was carried out.The simulation results showed that the thickness of the air layer of 75 mm,the total area of the vent holes of 0.24 m^(2),and the thickness of the insulation layer of 120 mm were the optimal construction for the passive part;solar collector area of 28 m^(2),hot water storage tank volume of 1.4 m^(3),mass flow rate of 800 kg/h on the collector side,mass flow rate of 400 kg/h on the heat exchanger side,and output power of auxiliary heat source of 5∼9 kWwere the optimal constructions for active heating system.Test results showed that during the heating period,the system could provide sufficient heat to the room under different heating modes,and the indoor temperature reached over 18°C,which met the heating demand.The economic and environmental benefits of the system were analyzed,and the economic benefits of the systemwere better than coal-fired heating,and the CO_(2) emissionswere reduced by 3,292.25 kg compared with coalfiredheating.The results of the study showed that the combinedactive-passiveheating systemcouldeffectively solve the heating problems existing in rural buildings in Southern Xinjiang,and it also laid the theoretical foundation for the popularization of the combined heating systems.

Active-passive radial-additive friction stir repairing of mechanical hole out of dimension tolerance of AZ31 magnesium alloy

In order to avoid the depth increasing of repaired hole and eliminate the super-fine grain band in stir zone by radial-additive friction stir repairing(R-AFSR), a solid-state repairing technique of active-passive radial-additive friction stir repairing(AP-RAFSR) assisted by the truncated cone-shaped filling material was proposed in this study. The mechanical hole out of dimension tolerance of AZ31 magnesium alloy was chosen as the repaired object. The results indicated that the AP-RAFSR process rather than the R-AFSR process avoided the kissing bond in the bottom of the repairing interface under the condition of the tool pin length equal to the height of the standard mechanical hole.The continuously-distributed and large-length super-fine grain bands were eliminated in the stir zone by AP-RAFSR. The maximum tensile and compressive-shear strengths of repaired hole by AP-RAFSR reached 190.6 MPa and 138.9 MPa at 1200 rpm respectively, which were equivalent to 97.7% and 89.6% of those of the standard mechanical hole. This AP-RAFSR process assisted by the truncated cone-shaped filling material provides a new technique to obtain a no-depth-increasing, defect-free and high-strength repaired mechanical hole.

Robotic Walker for Slope Mobility Assistance with Active-Passive Hybrid Actuator

Walking assistance can be realized by active and passive robotic walkers when their users walk on even roads.However,fast signal processing and real-time control are necessary for active robotic walkers when the users walk on slopes,while assistive forces cannot be provided by passive robotic walkers when the users walk uphill.A robotic walker with an active-passive hybrid actuator(APHA)was developed in this study.The APHA,which consists of a rotary magnetorheological(MR)brake and a DC motor,can provide mobility assistance to users walking both uphill and downhill via the cooperative operation of the MR brake and DC motor.The rotary MR brake was designed with a T-shaped configuration,and the system was optimized to minimize the brake volume.Prototypes of the APHA and robotic walker were constructed.A control algorithm for the robotic walker was developed based on the characteristics of the APHA and the structure of the robotic walker.The mechanical properties of the APHA were characterized,and experiments were conducted to evaluate the mobility assistance supplied by the robotic walker on different roads.The results show that the APHA can meet the requirements of the robotic walker,and suitable assistive forces can be provided by the robotic walker,which has a simple mechanical structure and control method.

Mode-Coupling Theory for Glass Transition of Active-Passive Binary Mixture

Collective behaviours of active particle systems have gained great research attentions in re- cent years. Here we present a mode-coupling theory （MCT） framework to study the glass transition of a mixture system of active and passive Brownian particles. The starting point is an eff）ctive Smoluchowski equation, which governs the dynamics of the probability dis- tribution function in the position phase space. With the assumption of the existence of a nonequilibrium steady state, we are able to obtain dynamic equations for the intermediate scattering functions （ISFs）, wherein an irreducible memory function is introduced which in turn can be written as functions of the ISFs based on standard mode-coupling approximations. The effect of particle activity is included through an effective difIusion coefficient which can be obtained via short time simulations. By calculating the long-time limit of the ISF, the Debye-Waller （DW） factor, one can determine the critical packing fraction ηc of glass transition. We find that for active-passive （AP） mixtures with the same particle sizes, ηc increases as the partial fraction of active particle xA increases, which is in agreement with previous simulation works. For system with different active/passive particle sizes, we find an interesting reentrance behaviour of glass transition, i.e., ηc shows a non-monotonic dependence on xa. In addition, such a reentrance behaviour would disappear if the particle activity is large enough. Our results thus provide a useful theoretical scheme to study glass transition behaviour of active-passive mixture systems in a promising way.

Modeling and analysis of cantilever beam with active-passive hybrid piezoelectric network

The active-passive hybrid piezoelectric network (APPN) is investigated to reduce the vibration of cantilever beam. Hamilton's principle with the Rayleigh-Ritz method is used to derive the equations of motion of the beam with the APPN. Only one piezoelectric actuator is bonded on the cantilever beam, so in the segment of the beam where the piezoelectric actuator is attached, the neutral axis is not the geometric center of the beam. This change on the neutral axis is considered in the process of deriving equations. Selecting RL circuit as passive shunt circuit, open-loop analysis is performed to gain insight into the passive damping features. Velocity feedback control is then employed to analyze the characteristics of the closed-loop system. Numerical results show that the APPN has a significant effect on vibration suppression, especially at narrow frequency bands. On this basis, variable RL circuit is proposed and analyzed for broadband vibration attenuation. Numerical simulations illustrate that this scheme is effective and feasible.

Assessing the active-passive approach at variant incidence angles for microwave brightness temperature downscaling

The Terrestrial Water Resources Satellite(TWRS)campaign is a planned Chinese candidate satellite mission,and a one-dimensional synthetic aperture technology will be used,resulting in variant incidence angles for collecting synchronous active-passive observations at L-band,which would make brightness temperature(T_(b))downscaling especially challenging when aiming to improve the spatial resolution of soil moisture measurements.In this study,two active-passive T_(b) downscaling algorithms,the time-series regression(TSR)and spectral analysis(SA)algorithms,are assessed comprehensively based on airborne experimental datasets.The results with data collected during the Soil Moisture Experiment 2002(SMEX02)showed that both approaches could provide a reliable downscaled T_(b) at the same incidence angle.Based on the ground and airborne active-passive observations under variant incidence angles from the Soil Moisture Experiment in the Luan River(SMELR)it can be shown that the linear relationship between T_(b) andσis still robust under the case of variant incidence angles,and T_(b)(both h-and v-pol)is better correlated toσvv for most cases thanσhh.Both downscaling approaches can be applied to active-passive observations under varying incidence angles.Moreover,SA method performed better than the TSR method according to the lower RMSE values and higher correlation.

The energy distribution of a train impact process based on the active-passive energy-absorption method

This paper examines the energy-absorption characteristics of trains for active-passive safety protection.A one-dimensional collision-simulation model of traditional subway vehicles and active-passive safety vehicles was developed based on the multibody dynamics theory using MATLAB simulation software.The effectiveness of the simulation model was verified by scaled-collision tests.Then,the energy-absorption characteristics of traditional trains and the active-passive safety trains under different marshalling conditions were studied.The results showed that as the number of marshalling vehicles increased from 5 to 8,the energy absorption of interface 1 for the active-passive safety trains during the collision was 681 kJ,775 kJ,840 kJ and 901 kJ,and the physical compression of the interface of the head car of the active-passive safety trains was 619 mm,704 mm,764 mm and 816 mm,which was far below the maximum value of 1773 mm.The head car of the active-passive safety subway vehicles therefore had sufficient energy-absorption capacity.Finally,to find the maximum safe impact velocity of the active-passive safety trains,the energy distribution of the active-passive safety subway vehicles with 8-car marshalling at different impact velocities was studied.It was found that the safe impact velocity of an active-passive safety subway vehicle conforming to the requirements of the EN15227 collision standard reached 32 km/h,far exceeding the safe impact velocity of 25 km/h allowed by traditional trains,and representing an increase in the safe impact velocity of 28%.The total collision-energy absorption of the interface of the head car of the active-passive trains was 89.1%higher than that of the traditional trains at the safe impact velocity.The active-passive energy absorption method was therefore effective at improving the crashworthiness of the subway trains.

Effect of Active–Passive Deformation on the Thrust by the Pectoral Fins of Bionic Manta Robot

Bionic manta underwater vehicles will play an essential role in future oceans and can perform tasks,such as long-duration reconnaissance and exploration,due to their efficient propulsion.The manta wings’deformation is evident during the swimming process.To improve the propulsion performance of the unmanned submersible,the study of the deformation into the bionic pectoral fin is necessary.In this research,we designed and fabricated a flexible bionic pectoral fin,which is based on the Fin Ray®effect with active and passive deformation(APD)capability.The APD fin was actively controlled by two servo motors and could be passively deformed to variable degrees.The APD fin was moved at 0.5 Hz beat frequency,and the propulsive performance was experimentally verified of the bionic pectoral fins equipped with different extents of deformation.These results showed that the pectoral fin with active–passive deformed capabilities could achieve similar natural biological deformation in the wingspan direction.The average thrust(T)under the optimal wingspan deformation is 61.5%higher than the traditional passive deformed pectoral fins.The obtained results shed light on the design and optimization of the bionic pectoral fins to improve the propulsive performance of unmanned underwater vehicles(UUV).

Hybrid Active–Passive Prosthetic Knee:A Gait Kinematics and Muscle Activity Comparison with Mechanical and Microprocessor-Controlled Passive Prostheses

Existing microprocessor-controlled passive prosthetic knees(PaPKs)and active prosthetic knees(AcPKs)cannot truly simulate the muscle activity characteristics of the active–passive hybrid action of the knee during the normal gait.Differences in EMG between normal and different prosthetic gait for different phases were never separately analyzed.In this study,a novel hybrid active–passive prosthetic knee(HAPK)is proposed and if and how muscle activity and kinematics changes in different prosthetic gait are analyzed.The hybrid hydraulic-motor actuator is adopted to fully integrate the advantages of hydraulic compliance damping and motor efficiency,and the hierarchical control strategy is adopted to realize the adaptive predictive control of the HAPK.The kinematic data and EMG data of normal gait and different prosthetic gait were compared by experiments,so as to analyze the changes in the muscle activity and spatio-temporal data per phase compared to normal walking and the adaptations of amputees when walking with a different kind of prosthesis(the mechanical prosthesis(MePK),the PaPK and the HAPK).The results show that changes in prosthetic gait mainly consisted of decreased self-selected walking speed,gait symmetry and maximum knee flexion,increased first double support phase duration,muscle activation in both opposed and prosthetic limb and inter-subject variability.The differences between controls and MePK,PaPK and HAPK decreases sequentially.These results indicate that the hybrid active–passive actuating mode can have positive effects on improving the approximation of healthy gait characteristics.

Effect of a portable ultra-clean exponential airflow unit on the particle distribution in an operating room

The effects of a mobile laminar airflow unit on the concentration, deposition and distribution of bacteria- carrying particles in an operating room are investigated. The exploration is carried out using numerical calculation schemes （computational fluid dynamics approach）. The model validation was performed through result comparisons with published measurement data from literature. Two types of mobile screen units were evaluated as an extension of turbulent-mixing operating-room ventilation. Airborne particle concentration/sedimentation was recorded with and without a screen unit on the operating table and two instrument tables. Both active and passive air sampling were examined and the results are compared. It was found that the additional mobile ultra-clean laminar airflow unit reduces the counts of airborne bacteria and surface contamination to a level acceptable for infection-prone surgeries.

Understanding root-zone soil moisture in agricultural regions of Central Mexico using the ensemble Kalman filter,satellite-derived information,and the THEXMEX-18 dataset

An Ensemble Kalman Filter(EnKF)-based assimilation algorithm was implemented to estimate root-zone soil moisture(RZSM)using a Soil-Vegetation-Atmosphere Transfer(SVAT)model during a complete growing season of corn in Central Mexico.Synthetic and field soil moisture(SM)observations and NASA SMAP SM retrievals were used to understand the effect of vertically spatial updates and uncertainties in meteorological forcings on RZSM estimates.Assimilation of RZSM every 3 days using SM observations at 4 depths lowered the averaged standard deviation(ASD)and the root mean square error(RMSE)by 60%and 50%,respectively,compared to the open-loop ASD.The assimilation of synthetic SM at the top 0-5 cm obtained RZSM closer to observations compared to THEXMEX-18 SM measurements and SMAP SM retrievals.Differences between EnKF estimates and SM observations and SMAP SM retrievals are mainly due to misrepresentation of vegetation conditions.The results improved SM estimates up to 10-cm depth using SMAP SM retrievals;however,additional studies are needed to improve SM at deeper layers.The implemented methodology can estimate SM at the top 10 cm of the soil every 3 days to mitigate the impact of the climate change on agricultural production over rainfed areas,particularly in developing countries.