COMPARISON OF EMITTED EMISSIONS BETWEEN TRENCHLESS PIPE REPLACEMENT AND OPEN CUT UTILITY CONSTRUCTION

Currently,there is a worldwide trend towards reducing emissions into the environment generated by human activities.Pollutant emissions into the atmosphere are a major measure of the impact on environment.The construction indus-try is a major producer of such emissions due in part to the magnitude of operations and the vast array of equipment.Increased urbanization has resulted in a need for the installation of an expanded underground network of infrastruc-ture that includes gas,water,wastewater,pipelines,power,and communications systems.Today,engineers are faced with engaging the construction option that not only provides the best cost advantage,but also considers environmental sensitivities to create the most sustainable solution.Reduction of pollutants such as carbon dioxide(CO_(2)),carbon monoxide(CO),nitrogen oxide(NO_(X)),total organic compounds(TOC),and sulfur oxide(SO_(X))have been identified by the United States Environmental Protection Agency as critical to sustainable development.This paper describes an approach for quantifying airborne emissions that is demonstrated through a comparison of two construction methods for installing a wastewater line.It was discovered that the option involving a traditional open cut method resulted in an overall average of about 80%greater emissions compared to trenchless pipe replacement.Thefindings of this paper should assist the utility construction industry in technology selection to minimize environmental impacts.

基于改进蚁群算法的多机器人任务分配

任务分配是多机器人系统需要解决的首要问题.针对传统蚁群算法求解多机器人任务分配收敛速度慢且易陷入局部最优问题,提出了改进蚁群算法.考虑多机器人任务分配问题,建立多旅行商问题模型,采用蚁群算法优化出解空间,然后采用遗传算法中的变异算子对每个机器人执行任务的顺序进行优化,并根据模拟退火过程中Metropolis准则以一定的概率接受优化过程中较差的解.在复杂约束条件下,为解决蚁群算法收敛速度慢且易陷入局部极小问题,引入局部优化变异算子和改进模拟退火算法.仿真结果表明,改进蚁群算法可以更好的解决多机器人任务分配问题.

Charge-controlled compositional/microstructural regulations and electrochemical actuation performance of bulk nanoporous Ni-Pd alloys

Bulk nanoporous(np)metallic actuators have attracted increasing attention due to their large strain and low stimulation voltage.However,studies focusing upon the combined effect of composition and structure on the actuation performance of metallic actuators are relatively scarce,and its underlying mechanism needs to be clarified Herein,a series of bulk np-NiPd samples with differen compositions and microstructures were fabricated using a dealloying-coarsening-dealloying strategy and chargecontrolled electrochemical dealloying,and the process involves only one component of precursor alloy.It has been found that the np-NiPd cubes show a composition/structure-dependent mechanical property and electrochemical actuation performance.Specially,the npNi_(70)Pd_(30)sample with a homogeneously porous structure and good network connectivity exhibits significantly larger strain amplitude and faster strain rate than other hierarchically porous NiPd samples(np-Ni_(50)Pd_(50)and npNi_(20)Pd_(80)).Moreover,the np-Ni_(70)Pd_(30)sample demonstrates good actuation stability with high strain retention after hundreds of cycles.Notably,the maximum strain amplitude(1.17%)is even comparable to that of advanced leadfree piezoceramic,and the maximum strain rate exceeds those of many reported metallic actuator materials.Our work indicates that good network connectivity plays a vita role in facilitating large/fast strain response in metallic actuators.

CONSTRUCTION AND THE ENVIRONMENT:RESEARCH FOCI FOR A SUSTAINABLE FUTURE

A workshop was sponsored by the National Science Foundation that united many professionals and researchers from both the construction and the environmental fields to outline initial recommendations regarding the interaction of the built environment with the natural environment to develop research foci for a sustainable future.The workshop entitled Construction and the Environment:Research Foci for a Sustainable Future produced a final report identifying three main research focus areas:1.Data collection and monitoring of the impact and effectiveness of sustainable construction with the development of ubiquitous sensors and monitoring devices.2.Development of improved or novel construction materials with a focus on the full life-cycle of these materials.Included with this would be a national program for information collection and dissemination.3.Development of decision making tools and models.These models should include both sustainable designs incorporating human factors and also models representing the interactions between the natural and built environment.The intention is to develop methods that reduce negative interactions and promote positive ones.All these research foci must include a widespread educational component and should embrace substantial collaborative efforts between the social,physical and applied sciences and engineering communities,as well as the construction industry,government agencies and regulatory communities.

Derivation and conformity measurement of a popular explicit analytic Borowy 2C PV module model

A popular explicit analytic Borowy 2C PV module model is proposed for power generation prediction.The maximum power point and the open-circuit point which are calculated in this model cannot be equal to the data given by manufacturers under standard test condition(STC).The derivation of this model has never been mentioned in any literatures.The parameter forms of 2C model in this paper are more simplified,and the model is decomposed into a STC sub-model and an incremental sub-model.The STC model is derived successfully from an ideal single-diode circuit model.Relative error estimations are developed to do the conformity error measurements.The analysis results showed that though the biases at those critical points are very small,the conformity will depend on both of the two ratio values I_(m)/I_(sc) and V_(m)/V_(oc),which can be used to verify whether 2C model is applicable for the PV module produced by a particular manufacturer.

Soft wearable flexible bioelectronics integrated with an anklefoot exoskeleton for estimation of metabolic costs and physical effort

Activities and physical effort have been commonly estimated using a metabolic rate through indirect calorimetry to capture breath information.The physical effort represents the work hardness used to optimize wearable robotic systems.Thus,personalization and rapid optimization of the effort are critical.Although respirometry is the gold standard for estimating metabolic costs,this method requires a heavy,bulky,and rigid system,limiting the system’s field deployability.Here,this paper reports a soft,flexible bioelectronic system that integrates a wearable ankle-foot exoskeleton,used to estimate metabolic costs and physical effort,demonstrating the potential for real-time wearable robot adjustments based on biofeedback.Data from a set of activities,including walking,running,and squatting with the biopatch and exoskeleton,determines the relationship between metabolic costs and heart rate variability root mean square of successive differences(HRV-RMSSD)(R=−0.758).Collectively,the exoskeleton-integrated wearable system shows potential to develop a field-deployable exoskeleton platform that can measure wireless real-time physiological signals.

疏水SiO_(2)粒子的设计、制备及改性环氧树脂的研究

为了制备具有稳定超疏水性能的水性环氧树脂,以3-氨丙基三乙氧基硅烷(KH550)、γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)的碱性水解反应为基础,制备不同粒径(微米、亚微米、纳米)的改性二氧化硅,通过层层组装的接枝反应制备出具有多尺度效应的草莓状SiO_(2)多重粒子.同时,作为对比,制备表面光滑的单包覆层的疏水SiO_(2).通过红外光谱(FTIR)、核磁共振氢谱(NMR)、高分辨质谱(HRMS)等测试手段表征其结构,解析两类粒子的微观形貌和表面性能的异同.将自制改性粒子与水性环氧树脂WEP共混,在涂层表面构建粗糙的微纳结构,制备具有超疏水性能的水性环氧树脂涂料.采用示差扫描量热分析(DSC)和热重分析(TGA)表征涂料的共混性能及耐热性能;采用扫描电镜(SEM)和原子力测试(AFM)量化分析涂层特征及其表面形貌;采用接触角测试(WCA)表征水性涂层的超疏水性能及其表面能的变化规律.结果显示,相对于单层包覆的光滑粒子,多层次结构的改性SiO_(2)粒子迁移到环氧树脂表面,构建的微纳结构更有利于超疏水性能的形成,涂层具有明显的自清洁效应,而形成的粗糙涂层表面在苛刻环境中保持了结构的稳定性和持久性,体现出优异的耐磨和耐化学腐蚀性能.

Reinforcing carbonized polyacrylonitrile fibers with nanoscale graphitic interface-layers

Carbon fibers going through stabilization,carbonization,and graphitization heat-treatment stages will form continuous graphitic layers that are closely packed and preferentially aligned along the fiber axis,forming high mechanical stiffness or strength and electrical or thermal conductivity.The alignment of noncontinuous,powder-like graphene layers in polymers has been challenging due to the low bending modulus of a few-or even single-layered graphene,which causes aggregations or folding behaviors.This research demonstrates the leveraging of polymer-nanoparticle interactions to align graphene nanoplatelets(GNPs)in the polyacrylonitrile(PAN)matrix.An in-house designed spinning method produces a three-layered fiber that utilizes the interfacial interactions between each layer for graphene alignment between graphitic layers.This composite containing oriented GNPs significantly improves modulus(i.e.,42.3 to 74.6 GPa)and increases electrical conductivity for enhancing volatile organic compounds(VOCs)sensing behaviors.This research opens up a new scalable fabrication method for multilayered composites.

A Certificateless Threshold Public Key Encryption Scheme

The decryption participant＇s private key share for decryption is delegated by key generation center in the threshold IBE scheme.However,a key generation center which is absolutely trustworthy does not exist.So the author presents a certificateless threshold public key encryption scheme.Collaborating with an administrator,the decryption participant generates his whole private key share for decryption in the scheme.The administrator does not know the decryption participant＇s private key share for decryption.Making use of q-SDH assumption,the author constructs a certificateless threshold public key encryption scheme.The security of the scheme is eventually reduced to the solving of Decisional Bilinear Diffie-Hellman problem.Moreover,the scheme is secure under the chosen ciphertext attack in the standard model.

Biomineralized and chemically synthesized magnetic nanoparticles:A contrast

Magnetic nanoparticles(MNPS)have widely been synthesized through chemical processes for biomedical applications over the past few decades.Recently,a new class of MNPs,known as bacterial magnetosomes,has been isolated from magnetotactic bacteria,a natural source.These magnetosomes are magnetite or greigite nanocrystals which are biomineralized in the bacterial cell and provide magnet-like properties to it.Contrary to MNPs,bacterial magnetosomes are biocompatible,lower in toxicity,and can be easily cleared from the body due to the presence of a phospholipid bilayer around them.They also do not demonstrate aggregation,which makes them highly advantageous.In this review,we have provided an in-depth comparative account of bacterial magnetosomes and chemically synthesized MNPs in terms of their synthesis,properties,and biomedical applications.In addition,we have also provided a contrast on how magnetosomes might have the potential to successfully substitute synthetic MNPs in therapeutic and imaging applications.

Erratum to: Biomineralized and chemically synthesized magnetic nanoparticles: A contrast

Erratum to:Front.Mater.Sci.2020,14(4):387^401 DOI:10.1007/s 11706-020-0531-7 Page 391,the caption of Fig.3 uBiomineralization and role of magnetosome membrane proteins in synthesis of BM crystals in MTB(Magnetosome proteins:MamR,MamS,MamT,MamP,MamD,MamF,MamG,MamE(protease dependent),MamC,MamM,MamN,MamO,MamK,MamJ,MamE,Maml,MamL,MamQ,MamB)."

Aye-aye middle finger kinematic modeling and motion tracking during tap-scanning

The aye-aye(Daubentonia madagascariensis)is a nocturnal lemur native to the island of Madagascar with a unique thin middle finger.Its slender third digit has a remarkably specific adaptation,allowing them to perform tap-scanning to locate small cavities beneath tree bark and extract wood-boring larvae from it.As an exceptional active acoustic actuator,this finger makes an aye-aye’s biological system an attractive model for pioneering Nondestructive Evaluation(NDE)methods and robotic systems.Despite the important aspects of the topic in the aye-aye’s unique foraging and its potential contribution to the engineering sensory,little is known about the mechanism and dynamics of this unique finger.This paper used a motion-tracking approach for the aye-aye’s middle finger using simultaneous video graphic capture.To mimic the motion,a two-link robot arm model is designed to reproduce the trajectory.Kinematics formulations were proposed to derive the motion of the middle finger using the Lagrangian method.In addition,a hardware model was developed to simulate the aye-aye’s finger motion.To validate the model,different motion states such as trajectory paths and joint angles,were compared.The simulation results indicate the kinematics of the model were consistent with the actual finger movement.This model is used to understand the aye-aye’s unique tap-scanning process for pioneering new tap-testing NDE strategies for various inspection applications.