The effect of controllable train-tail devices on the longitudinal impulse of the combined trains under initial braking

The 20,000-ton combined train running has greatly promoted China’s heavy-haul railway transportation capability. The application of controllable train-tail devices could improve the braking wave of the train and braking synchronism, and alleviate longitudinal impulse.However, the characteristics of the controllable train-tail device such as exhaust area, exhaust duration and exhaust action time are not uniform in practice, and their effects on the longitudinal impulse of the train are not apparent,which is worth studying. In this work, according to the formation of the Datong-Qinhuangdao Railway, the train air brake and longitudinal dynamics simulation system(TABLDSS) is applied to establish a 20,000-ton combined train model with the controllable train-tail device, and the braking characteristics and the longitudinal impulse of the train are calculated synchronously with changing the air exhaust time, exhaust area, and action lag time under initial braking. The results show that the maximum coupler force of the combined train will decrease with the extension of the continuous exhaust time, while the total exhaust time of the controllable train-tail device remains unchanged;the maximum coupler force of the combined train reduces by32.5% with the exhaust area increasing from 70% to 140%;when the lag time between the controllable train-tail device and the master locomotive is more than 1.5 s, the maximum coupler force of the train increases along with the time difference enlargement.

Evaluation of mercury speciation and removal through air pollution control devices of a 190 MW boiler

Air pollution control devices （APCDs） are installed at coal-fired power plants for air pollutant regulation. Selective catalytic reduction （SCR） and wet flue gas desulftLrization （FGD） systems have the co-benefits of air pollutant and mercury removal. Configuration and operational conditions of APCDs and mercury speciation affect mercury removal efficiently at coal-fired utilities. The Ontario Hydro Method （OHM） recommended by the U.S. Environmental Protection Agency （EPA） was used to determine mercury speciation simultaneously at five sampling locations through SCR-ESP-FGD at a 190 MW unit. Chlorine in coal had been suggested as a factor affecting the mercury speciation in flue gas; and low-chlorine coal was purported to produce less oxidized mercury （Hg^2＋） and more elemental mercury （Hg^0） at the SCR inlet compared to higher chlorine coal. SCR could oxidize elemental mercury into oxidized mercury when SCR was in service, and oxidation efficiency reached 71.0%. Therefore, oxidized mercury removal efficiency was enhanced through a wet FGD system. In the non-ozone season, about 89.5%-96.8% of oxidized mercury was controlled, but only 54.9%-68.8% of the total mercury was captured through wet FGD. Oxidized mercury removal efficiency was 95.9%-98.0%, and there was a big difference in the total mercury removal efficiencies from 78.0% to 90.2% in the ozone season. Mercury mass balance was evaluated to validate reliability of OHM testing data, and the ratio of mercury input in the coal to mercury output at the stack was from 0.84 to 1.08.

Orthogonal analysis of water model study on the optimization of flow control devices in a six-strand tundish

Improper flow control devices in a multi-strand tundish can cause some problems, for example, liquid steel cannot reach every nozzle at the same time and the liquid steel in nozzles far away from the entry zone has a lower temperature. The water model experiment of a six-strand tundish of Tianjin Iron ＆ Steel Co. Ltd. was performed, a new ＂U＂ type baffle was obtained, and its parameters were defined by perpendicular analysis. The ＂U＂ baffle can not only improve those imperfections, but also prolong the residence time of nonmetallic inclusions, which is good for their flotation and separation.

Improvement of tundish shape and optimization of flow control devices for sequence casting heavy steel ingots

The metallurgical effect of a round tundish used to cast heavy steel ingots in machine works at present was evaluated through water modeling experiments. The flow control devices of the improved oval tundish, which was used instead of the round tundish, had been optimized. The results show that the residence time of the round tundish is short, its inclusion removal efficiency is too low, and it has more dead zones and an unreasonable flow field. Compared with the round tundish, the improved oval tundish with the optimized weir and dam has a better effect： its minimum residence time is prolonged by 38.1 s, the average residence time is prolonged by 233.4 s, its dead volume fraction decreases from 26% to 15%, and the ratio of plug volume fraction to dead volume fraction increases from 0.54 to 1.27. The inclusion removal efficiency also increases by 17.5%.

Control devices incorporated with shape memory alloy

Abstract： Shape Memory Alloy （SMA） is a type of material that offers some unique characteristics for use in devices for vibration control applications. Based on SMA＇s material properties, fottr types of control devices that incorporate NiTi SMA wires are introduced in this paper, which include three types of dampers （SMA damper, SMA-MR damper and SMA-friction damper） and one kind of isolation bearing （SMA-rubber bearing）. Mechanical models of these devices and their experimental verifications are presented. To investigate the control performance of these devices, the SMA-MR damper and SMA-rubber bearing are applied to structures. The results show that the control devices could be effective in reducing the seismic response of structures.

Optimization of flow control devices in a tenstrand billet caster tundish

The physical model of a ten-strand billet caster tundish was established to study the effects of various flow control devices on the melt flow. Before and after the optimization of the melt flow, the inclusion removal in the tundish was evaluated by plant trials. The physical modeling results show that when combined with a baffle, the turbulence inhibitor, instead of the impact pad, can significantly improve the melt flow. A turbulence inhibitor with a longer length of inner cavity and without an extending lip at the top of the sidewall seems to be efficient in the improvement of the melt flow. Various types and designs of baffles all influence the flow characteristics significantly. The "V" type baffles are better than the straight baffles for flow control. The "V" type baffle with four inclined holes at the sidewall away from the stopper rods is better in melt flow control than the one with one inclined hole at each sidewall. The combination of a well-designed turbulence inhibitor and an appropriate baffle shows high efficiency on improving the melt flow and an optimal proposal was presented. Plant trials indicate that, compared with the original tundish configuration in prototype, the inclusions reduce by 42% and the inclusion distribution of individual strands is more similar with the optimal one. The optimal tundish configuration effectively improves the melt flow in the ten-strand billet caster tundish.

MODES COMPUTATION AND ANALYSIS FOR LONG MULTI-SPAN BUNDLE CONDUCTORS OF POWER TRANSMISSION LINES WITH GALLOPING CONTROL DEVICES

A new type of element which is suitable for solving the modes of thegalloping long multi-span bundle conductor structures is presented. The element is composed of allsub-conductor segments between two spacers. Based on the linearized governing differential equationsof the conductors, the mass matrix and stiffness matrix of the element in consideration of theconstrained relations imposed on the conductors by spacers are derived. The dynamic characteristicsof the galloping control devices can be directly added to the element. The modes for an actual powerline structure are computed by using the element formula and FEM procedures, where seven cases ofdifferent galloping control device allocations are considered. Compared with the measured data, themethod is shown to be reliable and effective. Analysis and discussions of the computational resultsare given. Some hints that are helpful to further investigation of galloping are also obtained .

Thermodynamic Modeling and Simulation of Air System Control Device

This paper aims to obtain the thermodynamic characteristics of the air system control device sealing part in different compressor bleed air and ambient temperature.On the basis of considering the main factors affecting the heat exchange process and simplifying the physical model of the air system control device,the thermodynamic model of air system control device is established based on the basic theory of laminar flow heat transfer and heat conduction theory.Then the piston motion characteristics and the thermodynamic characteristics of the air system control device seal are simulated.The simulation results show that the valve actuation dynamic time of piston is about 0.13 s in the actual working conditions,and the temperature effect on the dynamic response of the piston rod is only 5 ms when the inlet air temperature at 300 ℃ and 370 ℃.The maximum temperature of the air system control device sealing part is not more than 290 ℃ under long time working condition of compressor air entraining.The highest temperature of the sealing part can reach up to 340 ℃ when the air flow temperature reaches the limit temperature of 370 ℃,and the longest duration working temperature limit is not more than 14 s.Therefore,the selection of control device sealing material should consider the work characteristic of instantaneous temperature limit.

Study on Mesh-Control Device for the Mesh Generator Based on Tree Structures

In this paper, a process of the quadtree mesh generation is described, then a mesh control device of the tree based mesh generators is analyzed in detail. Some examples are given to demonstrate that the mesh control device allows for efficient a priori and a posteriori mesh refinements.

LoRa Backscatter Network Efficient Data Transmission Using RF Source Range Control

Networks based on backscatter communication provide wireless data transmission in the absence of a power source.A backscatter device receives a radio frequency(RF)source and creates a backscattered signal that delivers data;this enables new services in battery-less domains with massive Internet-of-Things(IoT)devices.Connectivity is highly energy-efficient in the context of massive IoT applications.Outdoors,long-range(LoRa)backscattering facilitates large IoT services.A backscatter network guarantees timeslot-and contention-based transmission.Timeslot-based transmission ensures data transmission,but is not scalable to different numbers of transmission devices.If contention-based transmission is used,collisions are unavoidable.To reduce collisions and increase transmission efficiency,the number of devices transmitting data must be controlled.To control device activation,the RF source range can be modulated by adjusting the RF source power during LoRa backscatter.This reduces the number of transmitting devices,and thus collisions and retransmission,thereby improving transmission efficiency.We performed extensive simulations to evaluate the performance of our method.

A Windows bitmap-based numerically controlled sculpture method and its application

Bitmap （BMP） is a widely used format in image processing. With the combination of the digital image processing and computer numerically controlled （NC） techniques, we developed a bitmap-based NC single-step and multi-dot method. An example was provided to illustrate the application and principle of this bitmap-based method in our newly innovated sandblasting glass NC sculpture system.

Theoretical and experimental research on a new system of semi-active structural control with variable stiffness and damping

In this paper,a new system of semi active structural control with active variable stiffness and damping (AVSD) is suggested.This new system amplifies the structural displacement to dissipate more energy,and in turn,effectively reduces the structural response in the case of relatively small story drifts,which occur during earthquakes.A predictive instantaneous optimal control algorithm is established for a SDOF structure equipped with an AVSD system Comparative shaking table tests of a 1/4 scale single story structural model with a full scale control device have been conducted.From the experimental and analytical results,it is shown that when compared to structures without control or with the active variable stiffness control alone, the suggested system exhibits higher efficiency in controlling the structural response,requires less energy input,operates with higher reliability,and can be manufactured at a lower cost and used in a wider range of engineering applications.

Real-time and wearable functional electrical stimulation system for volitional hand motor function control using the electromyography bridge method

Voluntary participation of hemiplegic patients is crucial for functional electrical stimulation therapy.A wearable functional electrical stimulation system has been proposed for real-time volitional hand motor function control using the electromyography bridge method.Through a series of novel design concepts,including the integration of a detecting circuit and an analog-to-digital converter,a miniaturized functional electrical stimulation circuit technique,a low-power super-regeneration chip for wireless receiving,and two wearable armbands,a prototype system has been established with reduced size,power,and overall cost.Based on wrist joint torque reproduction and classification experiments performed on six healthy subjects,the optimized surface electromyography thresholds and trained logistic regression classifier parameters were statistically chosen to establish wrist and hand motion control with high accuracy.Test results showed that wrist flexion/extension,hand grasp,and finger extension could be reproduced with high accuracy and low latency.This system can build a bridge of information transmission between healthy limbs and paralyzed limbs,effectively improve voluntary participation of hemiplegic patients,and elevate efficiency of rehabilitation training.

Advances of phononics in 2012-2022

Due to its great potential applications in thermal management,heat control,and quantum information,phononics has gained increasing attentions since the first publication in Rev.Mod.Phys.841045(2012).Many theoretical and experimental progresses have been achieved in the past decade.In this paper,we first give a critical review of the progress in thermal diodes and transistors,especially in classical regime.Then,we give a brief introduction to the new developing research directions such as topological phononics and quantum phononics.In the third part,we discuss the potential applications.Last but not least,we point out the outlook and challenges ahead.

Flow Simulation of a Horizontal Well with Two Types of Completions in the Frame of a Wellbore–Annulus–Reservoir Model

Well completions are generally used to connect a reservoir to the surface so that fluids can be produced from orinjected into it. With these systems, pipe flows are typically established in the horizontal sections of slotted screencompletions and inflow control device (ICD) completions;moreover, an annular flow exists in the region betweenthe pipe and the borehole wall. On the basis of the principles of mass and momentum conservation, in the presentstudy, a coupling model considering the variable mass flow of the central tubing, the variable mass flow of theannular tubing and the reservoir seepage is implemented to simulate the wellbore–annulus–reservoir behaviorin the horizontal section of slotted-screen and ICD completions. In earlier models, only the central tubing variablemass flow and reservoir seepage flow were considered. The present results show that the closer the heel end, thegreater is the flow per unit length in the central tubing from the annulus. When external casing packers are notconsidered, the predicted production rate of the slotted screen completion, which is obtained using the variablemass flow model not taking into account the annulus flow, is 9.51% higher than the rate obtained using the (complete) model with annulus flow. In addition, the incomplete model forecasts the production of ICD completion ata 70.98% higher rate. Both models show that the pressure profile and flow profile of the borehole wall are relatively uniform in the wellbore–annulus–reservoir in horizontal wells.

Chopper-modulated gas chromatography electroantennography enabled using high-temperature MEMS flow control device

We report the design,fabrication and characterization of a microelectromechanical systems(MEMS)flow control device for gas chromatography(GC)with the capability of sustaining high-temperature environments.We further demonstrate the use of this new device in a novel MEMS chopper-modulated gas chromatography-electroantennography(MEMS-GC-EAG)system to identify specific volatile organic compounds(VOCs)at extremely low concentrations.The device integrates four pneumatically actuated microvalves constructed via thermocompression bonding of the polyimide membrane between two glass substrates with microstructures.The overall size of the device is 32 mm×32 mm,and it is packaged in a 50 mm×50 mm aluminum housing that provides access to the fluidic connections and allows thermal control.The characterization reveals that each microvalve in the flow control chip provides an ON to OFF ratio as high as 1000:1.The device can operate reliably for more than 1 million switching cycles at a working temperature of 300℃.Using the MEMS-GC-EAG system,we demonstrate the successful detection of cis-11-hexadecenal with a concentration as low as 1 pg at a demodulation frequency of 2 Hz by using an antenna harvested from the male Helicoverpa Virescens moth.In addition,1μg of a green leafy volatile(GLV)is barely detected using the conventional GC-EAG,while MEMS-GC-EAG can readily detect the same amount of GLV,with an improvement in the signal-to-noise ratio(SNR)of~22 times.We expect that the flow control device presented in this report will allow researchers to explore new applications and make new discoveries in entomology and other fields that require high-temperature flow control at the microscale.

Traffic control devices for deterring wrong-way driving： Historical evolution and current practice

Each year, hundreds of fatal wrong-way driving （WWD） crashes occur across the United States. Thousands of injuries are reported in crashes caused by wrong-way drivers. Traffic control devices （TCDs）, i.e., signs, pavement markings, and signals, have been introduced since 1935 to combat this problem. The aim of the paper is to provide a complete history of TCDs for deterring WWD on freeways and divided highways in previous versions of the Manual on Uniform Traffic Control Devices （MUTCD） （1935-2009）. A fully referenced overview of definitions, text passages, and figures of the TCDs, employed to deter WWD in all MUTCD versions, will be given to characterize the changes over time. In addition, the efforts that have been made by state department of transportation （DOT） especially over the past few years to aggressively attack WWD by deploying standard TCDs are reviewed. Finally, the paper makes conclusions and recommendations with regard to the necessity of a revision in the next edition of MUTCD for WWD TCDs. The investigation of changes and the current practice leave a trail to enable traffic engineers and policy makers to consider past decisions and their effectiveness in combating WWD, as well as providing a reference to determine whether or not their jurisdiction meets the MUTCD standards.

Optimal economic operation of isolated community microgrid incorporating temperature controlling devices

With the increasing connection of controllable devices to isolated community microgrid,an economic operation model of isolated community microgrid based on the temperature regulation characteristics of temperature controlling devices composed of wind turbine,micro-gas turbine,energy storage battery and heat pump is proposed.With full consideration of various economic costs,including fuel cost,start-stop cost,energy storage battery depletion expense and penalty for wind curtailment,the model is solved by hybrid particle swarm optimization(HPSO)algorithm.The optimal output of the micro-sources and total operating cost of the system in the scheduling cycle are also obtained.The case study demonstrates that temperature adjustment of temperature controlling devices can adjust the power load indirectly and increase the schedulability of the isolated community microgrid,and reduce the operating cost of the microgrid.

Physical and numerical investigation on fluid flow and inclusion removal behavior in a single-strand tundish

Aiming at the problem that the existence of inclusions in the tundish continuous casting process can easily lead to quality defects of the slab,the stainless steel continuous casting tundish was taken as the research object.The effects of flow control device,inclusion density and inclusion size on the mixing characteristics of molten steel and inclusion behavior in tundish were studied.The results showed that compared with the tundish without flow control device,the average residence time of molten steel was prolonged by about 49 s,the dead zone volume fraction was reduced by 8.93%,and the piston fluid integral rate was increased by 12.68%.In the turbulence inhibitor(TI)tundish with weir-dam combination,the removal rate of inclusions with a density of 2700 kg m^(-3) and a particle size of 5 lm is 63.32%,while the removal rate of large inclusions with a density of 150μm could reach 89.04%.When the inclusion particle size was 10-50μm and the density was 2700-4500 kg m^(-3),the effect of inclusion density on inclusion removal rate was small.At the same time,when weir-dam combination TI tundish was set,the inclusions were mainly limited to the slag-metal interface of the first and second chambers of the tundish.The removal rate of inclusions in the first chamber was generally improved,with 10μm inclusions accounting for 47.67% and 150μm inclusions accounting for 60.69%.Furthermore,it has the best effect on the removal of small-size inclusions,especially those less than 70μm.

Emission control and phase migration of PCDD/Fs in a rotary kiln incinerator:hazardous vs medical waste incineration

This study was carried out in a full-scale(50 t/d)rotary kiln incinerator to explore the removal characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)by different units of air pollution control devices(APCDs),and special interest was focused on the“memory effect”phenomenon of PCDD/Fs in the wet scrubber(WS),which usually caused an undesirable rise in PCDD/F emission concentrations.The general removal efficiency of PCDD/Fs by APCDs was 99.4%(from 14.11 at exhaust heat boiler(EHB)outlet to 0.09 ng I-TEQ/Nm^(3)at stack)under medical waste(MW)incineration condition,and 99.2%(from 19.91 to 0.16 ng I-TEQ/Nm^(3))under hazardous waste(HW)incineration condition.The PCDD/F concentrations in flue gas decreased along the APCDs except for WS,in which the“memory effect”was observed.In detail,WS largely increased the I-TEQ concentration of gas-phase PCDD/Fs from 0.047 to 0.188 ng I-TEQ/Nm^(3)in the flue gas,and the concentration of particulate-phase PCDD/Fs increased from 0.003 to 0.030 ng I-TEQ/Nm^(3).In addition,this study found that phase migration promoted the accumulation of PCDD/Fs in scrubbing water,and the flow entrainment phenomenon played a great role in causing the“memory effect”.The PCDD/F concentrations of fly ash collected from cyclone and fabric filter(FF)were as high as 4.23 and 6.99 ng I-TEQ/g,respectively,which had exceeded the national landfill limitation(3 ng I-TEQ/g)in China.The system balance calculations revealed that APCDs promoted the migration of PCDD/Fs from the gas-phase to the particulate-phase,which caused fly ash to be the main carrier of PCDD/Fs and led to excessive emissions.The results of this study can contribute to the optimized design of combustion conditions and system cleaning for controlling PCDD/F emissions from rotary kiln incinerators.