Spatiotemporal phase change materials for thermal energy long-term storage and controllable release

Phase change materials(PCMs)have attracted much attention in the field of solar thermal utilization recently,due to their outstanding thermal energy storage performance.However,PCMs usually release their stored latent heat spontaneously as the temperature below the phase transition temperature,rendering thermal energy storage and release uncontrollable,thus hindering their practical application in time and space.Herein,we developed erythritol/sodium carboxymethylcellulose/tetrasodium ethylenediaminetetraacetate(ERY/CMC/EDTA-4Na)composite PCMs with novel spatiotemporal thermal energy storage properties,defined as spatiotemporal PCMs(STPCMs),which exhibit the capacity of thermal energy long-term storage and controllable release.Our results show that the composite PCMs are unable to lose latent heat due to spontaneous crystallization during cooling,but can controllably release thermal energy through cold crystallization during reheating.The cold-crystallization temperature and enthalpy of composite PCMs can be adjusted by proportional addition of EDTA-4Na to the composite.When the mass fractions of CMC and EDTA-4Na are both 10%,the composite PCMs can exhibit the optical coldcrystallization temperature of 51.7℃ and enthalpy of 178.1 J/g.The supercooled composite PCMs without latent heat release can be maintained at room temperature(10-25℃)for up to more than two months,and subsequently the stored latent heat can be controllably released by means of thermal triggering or heterogeneous nucleation.Our findings provide novel insights into the design and construction of new PCMs with spatiotemporal performance of thermal energy long-term storage and controllable release,and consequently open a new door for the development of advanced solar thermal utilization techniques on the basis of STPCMs.

Effects of a New Long-term Controlled-release Fertilizer on Growth and Development and Yield of Summer Maize

[Objective] The aim was to select the optimal amount of controlled-release fertilizer and provide theoretical references for controlled-release fertilizers use in summer maize. [Method] Long-term controlled-release fertilizers were applied once at sowing summer maize to explore effects on maize growth, yield, economic profits and environment. [Result] Maize yield reduced a little in the treatment group with 60% CRF, and increased in varying degrees in the rest groups in the range of 1.1%-7.4%, and some showed significant differences. [Conclusion] Controlled-release fertilizers can be applied once at the amount of 80% common fertilizer＇s, with con- sideration of maize yield, nitrogen use rate and economic profits, which is beneficial for summer maize application and promotion in North China.

Survey of <i>C. difficile</i>-Specific Infection Control Policies in Local Long-Term Care Facilities

Introduction: The incidence and severity of Clostridium difficile infection (CDI) has been increasing and long-term care facility (LTCF) residents are at high risk given their age, co-morbidities, and high antibiotic exposure. Infection control policies are crucial for controlling CDI, but there are currently no regulatory guidelines in the United States. Therefore, we evaluated infection control policies in local LTCFs to define the CDI-specific policies and the administrative and staff understanding of CDI, so as to identify perceived barriers for compliance. Methods: IRB approval was sought and exemption granted, all 8 local LTCFs were asked to participate. Each facility was visited by study personnel who interviewed the administrative Infection Control Practitioner (ICP) and 3-4 Licensed Practical Nurses (LPNs) with distinct survey format. Infection control policies were then compared to the SHEA recommendations for CDI in LTCFs. Results: Of the eligible facilities, 75% (n = 6) participated. ICP (n = 6) and LPNs (n = 21) were interviewed. All facilities accept residents with active CDI and 2 had written CDI-specific infection control policies. All facilities had hand hygiene or glove use policies and 2 had policies for the use of sporicidal environmental cleaning. No facility restricted antibiotic use. Each facility has a policy to instruct their staff through in-services, either annually or upon new hire, but 33% (n = 7) LPNs reported no facility-based CDI training. While 80% (n = 17) of LPNs felt comfortable with the facility CDI policies, only 11 accurately restated it. ICPs felt the most relevant barrier to staff compliance was time constraints (n = 4, 67%), however, LPNs felt it was limited knowledge (n = 10, 48%) and poor communication (n = 2, 10%). Discussion and Conclusions: With the increasing incidence and severity of CDI in LCTF, few of the facilities surveyed had CDI-specific policies. Despite CDI-specific training, there is a perceived knowledge and communication gap for staff caring for residents with CDI.

Long-term stabilization of the optical fiber phase control using dual PID

We propose an approach of long-term stabilization of optical fiber phase by controlling a piezo-based phase modulator and a Peltier component attached to the fiber via a phase-locked loop( PLL) circuit w ith dual proportional-integral- derivative( PID) adjustment. With this approach,we can suppress the fast disturbance and slow drifting of optical fiber to satisfy the requirements of optical phase long-term locking. In theory,a mathematical model of an optical fiber phase control system is established. The disturbance term induced by environment influence is considered into the PLL model. The monotonous and continuous changing environment disturbance w ill cause a steady-state error in this theory model. The experimental results accords w ell w ith the theory. The steady-state performance,adjusting time,and overshoot can be improved by using the dual PID control. As a result,the long-term,highly stable and low noise fiber phase locking is realized experimentally.

Analysis and Control of Novel Deflection-Type PM Multi-DOF Actuator

This paper mainly presents a PM multi-DOF actuator for robot in-wheels drive applications and its control method. The torque model is established based on the finite-element model of the single pair poles in 3D finite element method software. Due to the special structure of the actuator,the Euler angles are adopted for deriving the kinematics and dynamic model. To reduce the effects of uncertainties of modeling error,nonlinear friction and external disturbances in the system,an approximation of neural network adaptive control method is applied to the actuator. The computation and simulation results show that the proposed analysis and control method can effectively derive the characteristics and improve the motion performance,which provides the primary theoretical guide for the configuration design,optimization and control research of multi-DOF deflection type actuators.

Fuzzy control method to minimize the needle deflection during needle insertion therapy

A fuzzy control algorithm is adopted to help the needle hit the target more accurately. The experimental setup for the needle insertion is built up to validate the algorithm. How the forces dur- ing the insertion make the needle deflect away from the planned path is given, and the normal meth- od correcting the deflection is obtained accordingly. Because the normal method cannot perform well for correction, a fuzzy controller is established. The input module, output module, fuzzification module, defuzzification module and inference engine for the controller are given respectively accord- ing to the fuzzy theory. Our experimental results show that the fuzzy controlling system presenting in the paper can better eliminate the deflection.

Arc deflection model and arc direction control for DC arc furnace

Based on the analysis of three-dimensional power conductor for DC arcfurnace, the electric arc deflection model was set up and the control system of the arc directionwas configured. According to the bus bar distribution at the bottom electrodes cooled by water, thearc direction control principle and its configuration were described. The simulation results showthat the control system can restrain the electric arc deflection and control the arc direction.

Numerical Simulation of Wake Deflection Control around NACA0012 Airfoil Using Active Morphing Flaps

This study demonstrates an active flow control for deflecting a direction of wake vortex structures behind a NACA0012 airfoil using an active morphing flap. Two-dimensional direct numerical simulations are performed for flows at the chord Reynolds number of 10,000, and the vortex pattern in the controlled and noncontrolled wakes as well as the effect of an actuation frequency on the control ability are rigorously investigated. It is found that there is an optimum actuation-frequency regime at around F + = 2.00 which is normalized by the chord length and freestream velocity. The wake vortex pattern of the well-controlled case is classified as the 2P wake pattern according to the Williamson’s categorization [1] [2], where the forced oscillation frequency corresponds to the natural vortex shedding frequency without control. The present classification of wake vortex patterns and finding of the optimum frequency regime in the wake deflection control can lead to a more robust design suitable for vortex-induced-vibration (VIV) related engineering systems.

Control Schemes for Driving Electro-optic Array Beam Deflectors

The beam deflectors based on electro-optic phased array（EOPA） is mainly described, and then an analysis on existing control schemes for driving the EOPA beam deflectors, based on custom hard-wired electronics or based on software in a microcontroUer, is made. Compared with these, a driving and control system for a multi-channel EOPA beam deflector is presented, in which the control assignment is implemented with a field programmable gate array（FPGA） chip. For different performance requirements, two control schemes, one with the serial scheme and another with the parallel scheme, have been explored and rapidly prototyped in Xilinx FPGA chips. With the control structures for the EOPA beam deflector, scanning rates of 588 kHz and 5 MHz can be respectivelv reached.

Bone Marrow Transplant Long-Term Survivors’ Satisfaction with Quality of Life: Comparison with a Control Group

Purpose: To evaluate the global quality of life (QoL) of survivors with 10-year or more post-transplant, and to identify risk factors that interfere with well-being. Methods: This is a prospective analytic transversal study with 214 survivors of Bone Marrow Transplant (BMT) and 264 healthy people identified among blood donors, treated as the control group, of both sexes, 18 years or older. The protocol includes a demographic-socioeconomic questionnaire, World Health Organization Quality of Life (WHOQOL) and the Karnofsky Performance Status Scale. Results: 53.7% of the survivor group members are satisfied with their QoL. A similar result can be found in the control group (54.2%). Chronological maturity, anxiety, sexual difficulty, and being a provider are factors that interfere negatively in the QoL of male survivors. In female survivors, the risk factors are anxiety, low educational level, not having a stable partner, being a provider, and not being Caucasian. Conclusions: Survivors are as satisfied with their QoL as the control group. QoL is understood as a perceptive process composed of objective (functional and relational capacity) and subjective phenomenon (perceptive composition).

Deflectable Nose Control for Bank-to-Turn Missile

It is an innovative try to control hypersonic bank-to-turn missiles using the deflectable nose and flaps. The higher control efficiency,faster response,better stability and compactness of the nose control are shown by comparing the deflectable nose control with the normal tail fin control. A mathematical model of the missile,which is time-varying,nonlinear and strong coupling,is establihsed by multi-body dynamics to be used for designing the controller. A robust controller of deflectable nose control is designed by variable structure control theory,selecting sliding mode surfaces with tracking error and its integral function,and considering parameter disturbance of the model. The simulation results show the controller can response quickly and track precisely. The deflectable nose control is proper for the bank-to-turn missile.

基于Arduino的SMA丝材智能修复损伤钢筋混凝土梁试验研究

为修复钢筋混凝土梁在使用阶段中由于材料老化、裂缝开展等原因造成的损伤,提出一种基于Arduino智能平台和形状记忆合金(Shape Memory Alloy,SMA,具有形状记忆效应和超弹性特性)的智能修复控制系统,根据挠度及裂缝控制原理,设计智能修复控制装置。该装置由输入模块、处理模块和输出模块组成,当检测到钢筋应变超过限值时,输出模块升高SMA丝材温度对梁体进行修复。为验证该智能修复装置的修复性能,设计对比梁A(无修复装置)与试验梁B(加装智能修复控制装置),在加载过程中对试验梁B进行3次修复,对2根梁的跨中挠度、钢筋应变及裂缝宽度等进行对比分析。结果表明:破坏时试验梁B的跨中挠度、裂缝宽度均小于对比梁A,并且在3次修复中试验梁B的跨中挠度、裂缝宽度和钢筋应变最大回复率分别为31.0%、47.0%和71.5%。说明该智能修复控制装置可以监测试验梁受损情况并激发SMA材料对试验梁实施修复,实现钢筋混凝土梁的智能修复。

垂直起降系统的互补滑模与情感神经网络控制

针对具有未知扰动的垂直起降机双闭环控制系统,提出一种基于连续径向基情感神经网络的互补积分滑模控制策略。建立了包含未知扰动项的垂直起降机的数学模型,为系统内外环分别设计滑模控制器和互补积分滑模控制器,基于对系统鲁棒性的考量,利用连续径向基情感神经网络逼近系统未知扰动项,给出神经网络权重的自适应律,形成一套新型的复合控制策略,利用Lyapunov方法分析了系统的稳定性。通过对垂直起降机的仿真实验与实物实验进行分析对比,证明了所设计的控制器具有更快的收敛速度、更高的跟踪精度和更佳的鲁棒性。

雪峰弧构造带钻孔轨迹控制关键技术研究

随着近年来矿产资源勘查要求的提高,岩心钻孔的深度及地层复杂性也不断加大,为能精准的钻遇靶区矿体以实现地质目的,对钻孔轨迹控制的要求越来越高。雪峰弧构造带部分工作区地层倾角大、软硬交替频繁、地层破碎,实际施工中地层造斜情况严重,随着孔深增加导致终孔轨迹与靶区矿体偏差较大,影响矿产资源勘查的精度和质量。通过对该工作区地层造斜情况的深入分析,在ZK1001钻孔绳索取心钻进施工中采用初级定向孔技术和满眼钻具工艺,大幅度提高了钻孔孔身质量,较好地实现钻孔轨迹控制。并通过试验不同的岩心钻具组合,提出了满眼钻具组合的优化意见和建议,为工作区岩心钻孔轨迹控制提供技术参考。

影响振荡射流分离控制效果的关键因素

为找出影响振荡射流对流场分离控制效果的关键因素,采用典型振荡射流激励器对偏转襟翼流场施加控制,通过数值模拟分析施加控制后的流场特点,总结了射流停滞的原因和影响;并对比不同扩张段、脉冲式和扫掠式振荡射流的控制效果,总结了射流扫掠范围对控制效果的影响。结果表明:射流向流场中传递动量的均匀程度和扫掠范围是影响控制效果的关键因素。射流向流场中传递动量越均匀,扫掠范围越大,则控制效果越好。激励器喉道过小会抑制射流偏转,使射流在出口两侧停滞,导致射流向流场中传递动量不均匀,因此偏转襟翼两侧的控制效果好于中部;增大扩张段会增大射流扫掠范围从而改善控制效果;脉冲式激励器内的尖劈会阻挡射流扫掠至其后方,导致射流扫掠范围小,偏转襟翼中部控制效果差。

一种单反馈通道振荡射流激励器设计

为了设计一种有利于分离控制的振荡射流激励器,选取单反馈通道的形式,重点研究第二喉道与扩张段参数对射流振荡特性与偏转襟翼分离控制效果的影响,并总结几何参数设计依据,完成激励器设计并对比了其与典型激励器的分离控制效果。结果表明:反馈段参数应使射流在混合段扩张部分的偏角最大;混合段参数应使射流附着于混合段壁面;第二喉道应使射流向流场中均匀传递动量,其过小或过大均会减小射流偏角并导致射流向流场中传递动量不均匀;扩张段扩张角应增大至刚好不阻挡射流偏转,过大会使扩张段内射流发生不对称附着现象;增大出口高度可以增大射流偏移量,但其过大会延长射流在扩张段两侧的停滞时间。不同激励器的分离控制效果对比表明,采用自主设计激励器时的偏转襟翼减阻量是采用典型激励器时的3.8倍。

太赫兹多维度相位调控反射超表面研究

数字编码超表面可以控制电磁波传输,受到了广泛关注。大多数报道的编码超表面基于几何相位或传输相位实现对反射或者透射线极化波和圆极化波的2π相位覆盖,限制了太赫兹波调控灵活性。提出传输相位和几何相位相结合排布超表面,在线极化太赫兹波入射下,基于传输相位机理设计的超表面产生了涡旋波束。根据几何相位原理,在圆极化太赫兹波入射下,设计的超表面产生了反射波束的偏转,超表面可以在多个频点产生涡旋波束,在0.9和1.2 THz处产生拓扑荷数l=1和l=2的涡旋波束,通过卷积生成偏折涡旋波束。最后设计聚焦超表面,实现了反射聚焦。研究结果表明,设计的超表面提供了一种多自由度的太赫兹波偏振和相位操控方法,在太赫兹系统具有广阔的应用潜力。

基于CarSim-Simulink联合仿真的牵引车转向控制策略研究

牵引车在承担林业运载作业时,由于林间路况复杂,因此多以低速运行,有较高的转向需求,且往往带有负载单位,所以更关注其行驶稳定性与转向灵敏性。利用CarSim软件构建牵引车物理模型与负载模型,基于Simulink软件进行牵引车控制策略的设计,结合二自由度动力学模型建立牵引车二自由度模型,以牵引车横摆角速度与质心侧偏角参数结合模糊控制理论对牵引车转向过程进行制动力矩反馈控制,另外根据牵引车四轮转向模式,引入前后轮转角比例控制策略。在CarSim-Simulink联合仿真平台下,结合林业作业复杂路况进行不同控制策略下牵引车低速行驶与转向试验。结果表明,采取的控制策略有效减少复杂路况下牵引车的转向半径,提升转向速度,并将质心侧偏角限制在较小范围,牵引车稳定性较高,且横摆角速度稳态值更接近理想状态,转向更加灵敏。

面向多阶段的无尾飞行器力矩控制分配方法研究

为满足不同飞行阶段对无尾飞行器气动性能的不同要求,提出一种多目标控制分配方法。首先,建立无尾飞行器非仿射舵效模型,对无尾飞行器控制分配问题进行数学描述。然后,提出增量式非线性控制分配方法。其次,对增量形式的次级性能指标与加权形式的综合性能指标进行构建。最后,基于有效集二次规划方法对多目标非线性控制分配问题进行求解,并进行仿真验证。在仿真场景中,与最小舵偏算例相比,最小阻力算例平均阻力系数降低了36.96%,最大升力算例平均升力系数增大了7.76%。实验结果证明了控制分配方法能在满足力矩分配误差最小的条件下,有效实现最小舵偏、最小阻力与最大升力等不同次级目标。

后浇带区域受力性能及临时支撑布置方法研究

对后浇带区域受力性能及临时独立支撑布置方法进行了研究.首先基于力学原理建立后浇带区域变形的计算模型,根据规范取后浇带所在跨跨度的1/1000作为支撑布置的挠度控制指标,推导出支撑布置计算判据,以此判定需要布置支撑的后浇带区域,提出后浇带临时支撑布设方案;然后总结支撑布置规律,给出支撑布设位置速查表;最后以具体工程为例验证所提出的支撑布设方案的适用性.