bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Study on the Performance Characteristics of Cylindrical Heat Pipes With Differing Wick Type
Authors: Mahdavi Mahboobe , Tiari Saeed , Solanki Ajaysinh , Pawar Vivek
Published: January 2019

In the current study, the performance of a high temperature, cylindrical heat pipe under various operating conditions is investigated numerically. To find the appropriate geometrical and working parameters of the heat pipe, a two-dimensional axisymmetric model is developed to describe the vapor and liquid flows and heat transfers in the vapor core, the wick, and the wall regions. Sodium and stainless steel are selected as the working fluid, the wick material, and the container material. The compressibility of the vapor and viscous dissipation are taken into account. In the wick region, the Darcy–Brinkman–Forchheimer model is applied to simulate the liquid sodium characteristics. The effect of wick type, heat input, and operating temperature are studied on the overall performance of the heat pipe as well as vapor and liquid pressure drops. Screen wick, sintered powder wick and felt wick are selected. The results showed that, for the selected wick types, the sintered powder wick resulted in the largest liquid pressure drop and the felt wick resulted in the lowest thermal resistance. In addition, the influence of operating temperature on thermal resistance diminishes with increasing temperature.
A Numerical Analysis of Heat Transfer Enhancement by Turbulence Generated From Swirl Flow by Twisted Tape
Authors: Abdullah Muhammad Azmain , Amin M. Ruhul , Ali Mohammad
Published: January 2019

Heat exchangers are widely used in heating and cooling devices. The primary challenge is to improve the efficiency of the heat transfer equipment. Researchers have utilized various techniques to achieve this goal. Using twisted tapes could significantly increase the heat transfer rate from a circular surface due to turbulence generated from swirl flow. To enhance the heat transfer rate by twisted tape, two types of arrangements namely: (i) plain twisted tape and (ii) altered twisted tape geometries are used. These arrangements result in swirl flows. For improving heat transfer through swirl flow, some important parameters such as Reynolds number, external surface temperature, friction factor, inlet pressure, and surface heat flux are also considered. To identify the aftereffect of the velocity of inlet water, several parameters namely: (i) external surface temperature, (ii) inlet pressure, (iii) external surface heat flux and (iv) twist ratio are varied. A numerical modelling using k-ε method is performed to evaluate the effects of turbulence from the twisted tape on the heat transfer rate. The objective is to analyze the improvement of heat transfer effectiveness due to the swirl flow. The change in the values of the resulting Reynolds number by changing the inlet fluid velocity from 0.1 ms−1 to 0.7 ms−1 and rotational speed from 200 rpm to 600 rpm is studied. It is observed that for such changes heat transfer increases by 17 percent. It is also observed that heat transfer is directly proportional to inlet pressure and inversely proportional to the increment of twist ratio. The rate of heat transfer increased from 17 percent to 19 percent when the angular velocity of the twisted tape is changed from the 0 rpm to 600 rpm while the velocity of the water inside the pipe is held constant at 0.7 ms−1. Higher heat transfer rate is observed with high inlet pressure. Likewise, higher value of the Nusselt number is observed with higher rotational speed of the twisted tape and higher velocity at the pipe inlet. In addition, it is also observed that when the twist ratio is changed from 4 to 6, the rate of heat transfer is diminished by 6 percent.
An Analysis of Harmonic Airloads Acting on Helicopter Rotor Blades
Authors: Riyad Iftekhar A. , Chakravarty Uttam K.
Published: January 2019

Rotary wing aircrafts in any flight conditions suffer from excessive vibration which makes the passengers feel uncomfortable and causes fatigue failure in the structure. The main sources of vibration are the rotor harmonic airloads which originate primarily from the rapid variation of flow around the blade due to the vortex wake. Unlike fixed wing aircrafts, helicopter wake consists of helical vortex sheets trailed behind each blade and remains under the rotor disk which induces vertical downwash velocities at chordwise and spanwise stations of the blade. In this study, a mathematical model is developed for rotor blades to compute the harmonic loads induced velocity at rotor blades for two flight conditions-vertical takeoff and landing, and forward flight. This method is useful for the performance analysis of rotor blade and selection of airfoils for the blade. The sectional lift, drag, and pitching moment are computed at a radial blade station for both flight conditions. The numerical integration of Biot-Savart relation are done for all the trailing and shed vortices to calculate the downwash through the rotor disc. The airloads are calculated using the relation between harmonic and inflow coefficients. The lift at a particular radial station is computed considering trailing and shed vortices and summing over each blade. Lifting-surface and lifting-line theories are applied to near wake and far wake, respectively, to calculate the downwash and inflow through the rotor disc. The results for lift are compared to the experimental flight-test data.
Design and Fabrication of Pneumatic Soft Gripper
Authors: Guo Zhonghua , Sun Zhongsheng , Li Xiaoning
Published: January 2019

In this paper, a pneumatic soft gripper is proposed with inspiration from sea anemone. The gripper is composed of an actuator and several silicone tentacles. With the power of compressed air, the soft actuator expands and folds the tentacles. The gripper wraps tentacles around the object and highly compliant tentacles conforms to the shapes of an object, enveloping and holding it. The physical model is fabricated with 3D printed PLA mold and silicone gel. The gripping mechanics are analyzed according to the experimental gripping operations. On basis of the experimental and analysis result, the compliant gripping is realized while the stability is to be increased. So the tentacle structure is then improved by multi-chamber soft body and vacuum jamming bag. The jamming bag is combined to the end of each tentacle, where the bag is filled with particles to conform to the object shape. Therefore, a reliable constraint is realized between the gripper and the object under vacuum conditions. The bending motion and shaping effect are verified through theoretical and experimental approaches. The important parameters in the vacuum jamming process are also obtained. With such device, soft adaptive bodies enlarges the contact area to adapt to the work-piece where vacuum jamming bags increase the gripping force and stability. It is convenient for universal gripping operation for objects with different shapes.
Intelligent Decision Making Approach for Performance Evaluation of a Robot-Based Manufacturing Cell
Authors: Kangru Tavo , Riives Jüri , Otto Tauno , Pohlak Meelis , Mahmood Kashif
Published: January 2019

Manufacturing is moving towards complexity, large integration, digitalization and high flexibility. A combination of these characteristics is a basic for forming a new kind of production system, known as Cyber Physical System (CPS). CPS is a board range of complex, multidisciplinary, physically-aware next generation engineered systems that integrates embedded computing technologies. Those integrated manufacturing systems usually consist of four levels: network, enterprise, production system and workplace. In this article we are concentrated to the workplace level, examining the implementation of the most suitable robot-cell and integration it into the production system and enterprise structure. The problem is actual for the big companies such as automobile industry, but very important is also for small and medium sized enterprises (SMEs) that tend to produce for example; small tractors, air conditioners for high speed trains or even different type of doors for houses. In all cases the best solution to response the situation is the implementation of robot-based manufacturing cell into a production system, which is not only a challenge but also need a lot of specific knowledge. Designing and selecting optimal solutions for robot-based manufacturing systems is suitable to carry out by a computer-based decision support systems (DSS). DSS typically works by ranking, sorting or choosing among the alternatives. This article emphasis to the problem of integration the DSS with the artificial intelligence (AI) tools. For this objective, the study has been focused to development of a conceptual model for assessing robot-based system by means of technical and functional capabilities, which is combined with cell efficiency based on process Key Performance Indicators (KPIs) and enterprise Critical Success Factors (CSFs). The elaborated model takes into consideration system design parameters, product specific indicators, process execution data, production performance parameters and estimates how the production cell objective can be achieved. Ten different types of companies were selected and their robot-based manufacturing systems were mapped by qualitative and quantitative factors based on the model, whereas executives were interviewed to determine companies’ strategic objectives. The study results comprise of an approach that helps SMEs to gain additional economic-technical information for decision making at different levels of a company.
Evaluation of In-Plane and Out-of-Plane Stresses in Composite Structures Subjected to Large Displacements/Rotations
Authors: Pagani Alfonso , Augello Riccardo , Carrera Erasmo
Published: January 2019

In many engineering applications, such as civil, mechanical and aerospace, large displacements and rotations may occur within the working composite structures, due to the extreme loading conditions that may occur during service. This afflicts the equilibrium states of the structures and could change them, eventually, in a catastrophic manner. Therefore, it may be necessary to predict the nonlinear stress conditions of the laminated structures through numerical simulation, in order to prevent the failure of the entire system.

To take into account these conditions, a geometrical nonlinear analysis has to be performed. The nonlinear framework proposed in this work is based on the Carrera Unified Formulation (CUF). CUF is a hierarchical formulation that considers the order of the structural model as an input of the analysis, so that no specific formulations are needed to obtain any refined model. The possibility to generate high-order structural elements makes possible to analyze any loading cases, including the post-buckling situation. Furthermore, this methodology allows to evaulate of the full three-dimensional stress tensor in laminated structures. In fact, as CUF is able to calculate the stiffness matrix in an automatic manner, there is no need to include any simplification to evaluate the out-of-plane components of the stress tensor.
Occupational Safety Implications of the Changing Energy Mix
Authors: Gernand Jeremy M.
Published: January 2019

Renewable energy and natural gas are displacing coal and nuclear power in many parts of the world as sources of electricity. While, the environmental benefits of such changes seem clear, the impact on worker safety, especially in developed nations is less clear. Coal mining is a relatively dangerous occupation, though one that has grown significantly safer in recent decades. Manufacturing and installation of solar photovoltaic (PV) power may pose less risk to workers on a per hour basis, but the number of worker hours necessary to generate a Megawatt-hour of electricity is currently higher for solar PV than it is for coal-generated power. The implications for the overall occupational burden of accidental deaths and injuries has not been previously detailed. This paper presents the results of a Monte Carlo sensitivity analysis for changes in total worker injuries and injury rates under different assumptions for the future energy mix in developed nations. Projections from the Energy Information Agency (EIA) and other organizations together with documented productivity gains for the various energy industries provide test cases for this analysis. The analysis indicates that future occupational fatality and injury burden of the energy sector is highly dependent on improvements in safety in the expanding industries, while specific projections on the share of specific technologies is less critical. This result highlights the need to invest in occupational risk mitigation in these industries.
Examining Ice Storage and Solar PV As a Potential Push Toward Sustainability for Qatar
Authors: Al-Aali Ibraheam , Modi Vijay
Published: January 2019

Soaring electricity demand from space cooling and excellent solar photovoltaics (PV) resources are creating an opportunity for the financial viability of low-emission solutions in Qatar that can compete with existing approaches. This study examines the big picture viability of combining large utility-scale PV with decentralized building-scale ice storage for cooling in Qatar. Qatar is found to have consistently high repeatable solar radiation intensity that nearly matches space cooling requirement. A means to exploit the low installed costs of PV, combined with low cost and long lifetime of ice storage (as opposed to batteries) are examined to meet space cooling loads. Space cooling is responsible for about 65% of Qatar’s annual electric load (which averaged 4.68 GW in 2016). While multiple gas prices are considered, a scenario with the current gas price of $3.33/MMBTU, a PV system of 9.7 GW capacity and an aggregate ice-storage capacity of 4.5 GWh could reduce the gas-fired power generation in Qatar by nearly 39%. Here, gas-fired generation capacity to meet current load exists and hence is not costed.
Fundamental Study of Multiple Slopes Exhibited by Measured Thermal Contact Conductance (TCC) Versus Load Data for Metal-Metal Contacts
Authors: Verma Navni N. , Mazumder Sandip
Published: January 2019

Experimental data of thermal contact conductance (TCC) between two metallic rough surfaces versus the applied load (pressure) distinctly exhibit non-linear behavior that can be split into two regimes with two distinct slopes. When the load is small, the rate of change of TCC with load is linear with a small slope. At intermediate loads, this slope increases. A third slope has been exhibited in some cases at extremely high loads — one in which the slope decreases again. In this study, two types of analysis are conducted on a simplified model system comprised of a single asperity compressed by two flat surfaces. The first analysis assumes one-dimensional heat conduction across the asperity, resulting in a fin-equation type model. In the second analysis, two-dimensional heat conduction through the asperity is considered, and the governing steady state heat conduction equation is solved numerically. Results show that the first two slopes at low and intermediate loads can be captured by both models. However, when the asperity is significantly depressed (high load regime) and deformed, the experimental behavior of the third reduced slope can only be captured by the two-dimensional numerical model. This implies that when the asperity deforms significantly, multi-dimensional heat transport becomes a critical limiting factor for the TCC.
Design and Testing of Liquid Cooled Thermal Solution for High Loading (Socket P) Processors
Authors: Soto Anali , Torreblanca Veronica , Kulkarni Devdatta
Published: January 2019

In recent years, semiconductor industry has manufactured processors which can be socketed and installed using specially designed retention mechanisms. Due to increased power and I/O capabilities for processors from generation to generation, the number of pins on the socket is increasing. This pin number increase is translated directly to increased retention loading force on thermal management solutions for reliable electrical contact and thermal interface material actuation. For recent generation of Intel® Xeon® Scalable Processor Family, a maximum retention force of 1334 N (300 lbf) needs to be transferred to the socket via thermal solution i.e. heat sink or cold plate. In liquid cooling applications, this high loading requirement calls for a stiffer cold plate.

At the same time, other regulatory and thermal requirements such as burst pressure and thermal performance need to be satisfied. A liquid cooled thermal solution was developed for the Intel® Xeon® Scalable Processor Family Platform. This thermal solution considers a modular bracket design which allows changing the material responsible for the load application on the thermal solution for a stronger and/or lighter one, without impacting the thermal performance due to material selection. This paper presents the design strategy, numerical analysis, test fixture setup for mechanical and thermal analysis, and prototype test results for mechanical and thermal performance of designed cold plates. This paper will be helpful to guide the thermal community to design a liquid cooled thermal solution for future generation of processors in data center applications and as well as for different electronic components.
Energy Harvesting From a Vehicle Damper by Using Electromagnetic Transducers
Authors: Xie Longhan , Li Jiehong
Published: January 2019

Hydraulic dampers are usually used to reduce the vibration of a vehicle, which convert the vibration energy into heat. Except for wasting energy, the unchangeable damping characteristic cannot adapt the various road conditions. Previous work on regenerative damper with changeable damping, which usually consist of one generator have some shortcomings, which consist of energy wasting and small range of damping tuning. Aiming at above problems, a new design principle with multiple-controlled generators is discussed in this paper. Furthermore, a new energy-harvesting damper with multiple-controlled generators (DMCG), which is based on the new design principle is designed. A prototype was built and tested by MTS testing system. The experiment results show that DMCG can not only tune the damping almost linearly, but also extract vibration energy as much as possible.
Higher-Order Shell Element for the Static and Free-Vibration Analysis of Sandwich Structures
Authors: Carrera Erasmo , Valvano Stefano , Filippi Matteo
Published: January 2019

An advanced shell finite element with a variable kinematic field based on a new zig-zag power function is proposed for the analysis of sandwich shell structures. The kinematic field is written by using an arbitrary number of continuous piecewise polynomial functions. The polynomial expansion order of a generic subdomain is a combination of zig-zag power functions depending on the shell thickness coordinate. As in the classical layer-wise approach, the shell thickness can be divided into a variable number of mathematical subdomains. The expansion order of each subdomain is an input parameter of the analysis. This feature enables the solution to be locally refined over generic regions of the shell thickness by enriching the kinematic field. The advanced finite shell elements with variable kinematics are formulated in the framework of the Carrera Unified Formulation. The finite element arrays are formulated in terms of fundamental nuclei, which are invariants of the theory approximation order and the modelling technique (Equivalent-Single-Layer, Layer-Wise). In this work, the attention is focused on linear static stress analysis and the free-vibration analysis of sandwich shell structures.
Image Identification of a Moving Object Based on an Improved Canny Edge Detection Algorithm
Authors: Liu Yang , Sun Lingyu , Li Lijun , Zhang Yiben , Dai Zongmiao , Xiong Zhenkai
Published: January 2019

Edge detection plays an increasingly critical role in image process community, especially for moving object identification problems. For this case, the target object can be captured straightly via the edges beside which there is an obvious jump of grey value or texture. Nowadays, Canny operator has gained great popularity as it shows higher anti-noise performance and presents better detection accuracy in comparison with other edge detection operators like Robert’s, Sobel’s, Prewitt’s etc. However, the Gaussian filter associated with the classic Canny operator is sometimes too simple to decrease the all-type-noise. Additionally, in order to enhance the detection accuracy and lower the pseudo-edges detection ratio, two thresholds, high and low, are chosen artificially which have actually limited the adaptability of the algorithm. In this work, a compound filter, Gaussian-Median filter, is proposed to improve the smoothing effect. The self-adaptive multi-threshold Otsu algorithm is realized to determine the high/low threshold automatically according to the grey value statistic. Image moment method is conducted on basis of the detected moving object edges to locate the centroid and to compute the principal orientation. The experimental results based upon locating the edges of both static and moving objects proved the good robustness and the excellent accuracy of the proposed method.
Numerical Investigation on Percolation Threshold of CNT-Reinforced Conductive Composites Based on Three-Dimensional Monte Carlo Method
Authors: He Zhuangzhuang , Li Lijun , Wang Taikun , Wang Yantao , Yang Xudong , Yang Wenming
Published: January 2019

It is reported that carbon nanotube (CNT)-based conductive polymer composites have potential application prospect in structural health monitoring and flexible sensors. However, the current price of CNTs is relatively high compared with other fillers. To reduce the materials cost and ensure the sensing characteristics of this type of materials, the most economic and least amount of CNTs needed should be found, this balance value is called as electrical percolation threshold (EPT) in this study. First, a large number of numerical models containing CNTs with three-dimensional random distribution and epoxy resin matrix are established by Monte Carlo method. Then, the construct of conductive network is observed using these models, and the influence of electron tunneling between two adjacent CNTs on the EPT is investigated. Furthermore, the influence of length-diameter ratio (L/D) of CNTs, length variation and angle distribution of CNTs on EPT is investigated. This research provides useful information on how to produce conductive composites more economically.
Periodic Motions in a First-Order, Time-Delayed, Nonlinear System
Authors: Xing Siyuan , Luo Albert C. J.
Published: January 2019

In this paper, periodic motions in a first-order, time-delayed, nonlinear system are investigated. For time-delay terms of non-polynomial functions, the traditional analytical methods have difficulty in determining periodic motions. The semi-analytical method is used for prediction of periodic motion. This method is based on implicit mappings obtained from discretization of the original differential equation. From the periodic nodes, the corresponding approximate analytical expression can be obtained through discrete finite Fourier series. The stability and the bifurcations of such periodic motions are determined by eigenvalue analysis. The bifurcation tree of period-1 to period-4 motions are obtained and the numerical results and analytical predictions are compared. The complexity of periodic motions in such a simple dynamical system is discussed.
Devices to Aid Mobility: Biomedical Engineering-Focused Undergraduate Senior Capstone Design Projects
Authors: Thompson Lara A. , Xu Jiajun , Shetty Devdas
Published: January 2019

In order to meet the increasing societal and market demand for a diverse and well-trained Biomedical Engineering (BME) workforce, the University of the District of Columbia (UDC), the nation’s only urban land-grant institution, the District of Columbia’s only public institution of higher education, and a historically black college and university (HBCU), nurtures BME activities focused on exposure, training and cultivation through research and experiential learning. Undergraduate design projects and research-based learning opportunities in BME are key program ingredients. This paper presents the former (i.e., three, BME-related undergraduate senior Capstone Design projects that target devices to aid patient immobility) namely, the design of: 1) an ankle foot orthosis, 2) an upperlimb robotic hand prosthetic, and 3) a chairless chair lower limb exoskeleton.

A current focus of the UDC BME program is Rehabilitation Engineering (i.e., interventions and devices aimed at aiding those with mobility impairments). We briefly discuss the necessity for rehabilitation-focused, biomedical-related undergraduate experiences and training for underrepresented minority students at UDC, in particular, undergraduate engineering education through multidisciplinary BME projects that foster hands-on creativity towards innovative designs.

In addition to critical design experiences and undergraduate training in BME, devices may have the potential to develop into new commercial technologies and/or research projects that will aid and enhance the quality life of individuals suffering from a wide-range of mobility-related issues.
Control for a Two-Link Planar Robot With an Actuated Tail
Authors: Yu Xinjia , Bedillion Mark
Published: January 2019

In this paper, a new climbing robot concept and its control strategy are introduced. The robot presented in this article is a two-link planar robot equipped with two magnetic grippers and one actuated tail, which is designed to add energy to the system for efficient climbing. The climbing strategy for this robot is inspired by brachiation robots. By alternating the activation of the grippers and using the tail to add energy, the robot can string together a sequence of pendulum-like paths with brachiation motion to reach any configuration on the climbing surface. Its high mobility and low energy consumption make this robot a candidate for applications in cleaning and inspection on vertical surfaces. The non-linear dynamics of the swinging motion for this robot are studied using the Lagrange formulation under the assumption that there is no slip on the grippers. The control strategy of this robot uses a high-level planner to determine the grip points and a low-level controller to actuate the tail, achieving low energy consumption with high accuracy. Model predictive control (MPC) is applied for the low-level swinging motion controller to determine the optimal torque provided to the tail. In this initial work the robot trajectory is planning based on minimization of the distance travelled. The performance of this robot is discussed based on MATLAB simulation results. The paper concludes by discussing alternative planning/control strategies along with initial work towards experimental validation.
Non-Linear Analysis of Bio-Structures Through Refined Beam Models
Authors: Guarnera Daniele , Carrera Erasmo , Kaleel Ibrahim , Pagani Alfonso , Petrolo Marco
Published: January 2019

A novel approach for the analysis of the non-linear behavior of bio-structures is presented here. This method is developed in the framework of the Carrera Unified Formulation (CUF), a higher-order 1D theory according to which the kinematics of the problem depends on the arbitrary expansion of the generalized unknowns. Taylor-like (TE) and Lagrange-like expansion functions (LE) are employed to describe the kinematic field along the cross-section and, the finite element method (FEM) is used to formulate the governing equations. In this work, the effects of material nonlinearities are investigated and, the problem is solved by using the Newton-Raphson method. An atherosclerotic plaque of an artery is introduced as a typical bio-structure with complex geometry and studied for both linear and non-linear material cases. The results from the proposed technique highlight the accuracy of the in-plane and out-of-plane stress/strain distributions for different 1D models. The 3D-like accuracy of local effect predictions, the possibility of dealing with complex geometries, and low computational costs of nonlinear analyses make the present formulation appealing for biomechanical applications.
Effect of Carbon Nanotube-Phosphinate Ionic Liquid Thin Boundary Layer on the Tribological Behavior of Aluminum Alloy in Steel-on-Aluminum Contact
Authors: Gutierrez Miguel A. , Gydesen Michael , Marcellus Caitlin , Puchades Ivan , Landi Brian , Iglesias Patricia
Published: January 2019

In this study, the tribological behavior of the Trihexyl tetradecylphosphonium-bis(2,4,4-trimethylpentyl)phosphinate [THTDP][Phos] ionic liquid with and without single-wall carbon nanotubes (SWCNT) dispersion as a thin boundary layer was intended for investigation. However, the surface heat treatment process was not sufficient to form a thin film on the sample surfaces. Thus, in each test condition, the lubricating agents were used as external (liquid) lubricants. Specifically, [THTDP][Phos] and ([THTDP][Phos]+0.1 wt.% SWCNT) boundary film layers were applied on 6061-T6 aluminum alloy disk samples and tested under sliding contact with 1.5 mm diameter 420C stainless steel balls using a ball-on-flat linearly reciprocating tribometer. A commercially available Mobil Super 10W-40 engine oil (MS10W40) was also tested and used as this investigation’s datum. The tribological behavior of [THTDP][Phos] and ([THTDP][Phos]+SWCNT) boundary film layers was analyzed via wear volume calculations from optical microscopy measurements, as well as by observation of the transient coefficient of friction (COF) obtained through strain gauge measurements made directly from the reciprocating member of the tribometer. Results indicate the potential for reduction of wear volume and coefficient of friction in the IL lubricated steel-on-aluminum sliding contact through (SWCNT) dispersion in the ionic liquid. Wear results are based on measurements obtained using optical microscopy (OM). Results discussed display improved tribological performance for both [THTDP][Phos] and ([THTDP][Phos]+SWCNT) over baseline MS10W40 oil lubricant for both roughness values tested for the steel-on-aluminum contact. No measurable improvements were observed between [THTDP][Phos] and ([THTDP][Phos]+SWCNT) tests.
Development of a Low Cost Self-Sustaining Water Distillation System Using Activated Carbon Nanofluids
Authors: Mishra Ashreet , Nnanna A. G. Agwu
Published: January 2019

There is an ever increasing need to provide clean and portable drinking water in developing countries because of the poor quality of water, which causes various water borne diseases killing millions of infants and elderly people every year. There have been a lot of recent developments in the field of solar enabled water distillation where pure water is being generated. But a majority of the system use some type of external energy source for the system to run on which might make it efficient but can cause dependence on energy sources. The power of the Sun can be effectively harnessed and used as heat and light source for efficient steam generation. One of the challenges is to develop a low cost system which can perform at par with the best and extravagant systems.

This paper investigates the performance of the solar distillation system when activated carbon nanoparticles are used along with brine and other sources of impure water so as to obtain clean water. The activated carbon nanoparticle which are an efficient and cheap mode of water purification enhanced the productivity of the system by 190% when compared to saline water due to its steam generation properties. A solar simulator of 1KWm2 was used to simulate the sun. Various parameters like the variation of air flow on condensation rate, height of fluid on vapor production rate and the temperature variation of the system are evaluated. Parametric studies of the effect of water quality and salinity were performed. It was determined that the optimum output rate of distilled water was 240 grams (6000gday.m2) was determined by the system from the parametric studies and the system is feasible and cost effective to be used in real world application. All of these standout features make the system a low cost option which can tackle the clean water dilemma in developing countries.
Effect of Passive Green Wall Modules on Air Temperature and Humidity
Authors: Abdo Peter , Huynh B. P.
Published: January 2019

Green walls are bio-filters developed to enhance air quality. Often, these walls form the base from which plants are grown; and the plant-wall system helps to remove both gaseous and particulate air pollutants. Green walls can be found indoors or outdoors and they are classified as passive or active systems. Their benefits include temperature reduction, improvement of air quality and reduction of air pollution, oxygen production as well as the social and psychological wellbeing. They can produce changes in the ambient conditions (temperature and humidity) of the air layers around them which create an interesting insulation effect. The effect of passive green wall modules on the air temperature and on humidity is investigated in this work. A closed chamber made of acrylic sheets is used to monitor the temperature and humidity variation caused by a green wall module placed at its center. Temperature and humidity are measured at different locations inside the chamber during operation for different modules with different plant species.
Molecular Dynamics Simulation of Explosive Boiling on Concave Nanostructured Surface
Authors: Ji Pengfei , He Mengzhe , Rong Yiming , Zhang Yuwen , Tang Yong
Published: January 2019

Explosive boiling occurs when a liquid film contacts with the wall at extremely high temperature, which is detrimental to continuous heat transfer process. In this paper, five kinds of nanostructured surfaces with equal distance between neighboring nano-concaves and flat surface are set up to study the explosive boiling of liquid argon on copper surface. For all the five cases with concave nanostructured surface, the ratio of concave nanostructured surface area to flat surface area is kept as a constant. The temporal and spatial distributions of temperature, atomic motion and number density are recorded to study the effects of different nanostructured surface designs on explosive boiling. From the perspective of reducing explosive boiling, the most favorable nanostructured surface is determined.
Dynamic Exposure Model of Scanning Beam Interference Lithography
Authors: Lu Sen , Yang Kaiming , Zhu Yu , Wang Leijie , Zhang Ming
Published: January 2019

To obtain desired photoresist grating by scanning beam interference lithography (SBIL), a precise exposure dose is demanded. For it is difficult to apply the real-time exposure monitoring technology in SBIL, a precise dynamic exposure model is needed to predict the groove profile of the photoresist grating. In this paper, a novel dynamic exposure model is established based on the characteristics of SBIL. Considering the nonlinear properties of the photoresist, a three-dimensional development process simulation is conducted based on cellular automata (CA) model. Based on this model, the influence mechanism of exposure parameters on groove profile can be analyzed, which provides an effective analysis method for optimizing exposure parameters of SBIL.
An Improved Optimal Adaptive Control Method for MIMO Sine Vibration Control of a Multichannel Coupled System
Authors: Li Chao , Chen Zhangwei , Zu Hongfei , Zhao Yugang
Published: January 2019

This paper proposes an improved optimal adaptive control algorithm to accelerate convergence for sine control of general multichannel coupled system, as well as enhance the stability. First of all, the convergence of traditional multi-input multi-output (MIMO) sine control method is analytically investigated in the presence of frequency response function (FRF) error. Then, the controller with the improved optimal adaptive control algorithm is developed, where a high-precision algorithm for amplitude and phase estimation is proposed to guarantee the accuracy of the response vector calculation. Numerical simulation results show that the proposed method possess excellent performance with fast convergence rate and strong robustness.
Analysis of Reciprocating Seals in the Wet-Mate Electrical Connectors for Underwater Applications
Authors: Han Quan , Zhang Yan , Chen Haiyang , Yang Juekuan , Chen Yunfei
Published: January 2019

In order to complete the mating and demating operations of the electrical connectors for underwater applications in the deep water environment, the pressure-balanced oil-filled (PBOF) structures are designed to compensate the huge water pressure. This paper focuses on the sealing performance of three sealing systems used in connectors, including the O-ring seals, rectangular seals, and U-cup seals. A method coupled the finite element analysis and elastohy-drodynamic lubrication (EHL) numerical model is presented to describe the issue. Results show that the rectangular seals perform best in fluid leakage, and O-ring seals are better in reducing the friction force. The oil leakages of the seals increase with the speed while the seawater leakages remain roughly constant. And the oil leakages of all the seals are larger than the seawater leakage. Types of seal rings, fluid viscosity and operation speed of connector can all influence the sealing performance of wet-mate connectors.
Reduction of Jerk Through Optimization of a Knee Assistive Device Designed Using Four-Bar Controlled Compliance Actuator
Authors: Sahoo Saikat , Jain Aditya , Pratihar Dilip Kumar
Published: January 2019

Two major responsibilities are taken by a knee joint during level ground walking of a human being. At stance phase, knee joint is locked in order to provide stability against ground reaction force, and in swing phase, knee flexes for ground clearance of the foot. In this study, a four-bar controlled compliance actuator (FCCA) has been configured for assisting the knee joint during walking. The main focus of FCCA design is the reduction of required mechanical power through a compliance actuation strategy and amplification of motor power. The proposed design consists of two linear spring-damper systems, out of which, one controls the locking of knee during stance phase and another takes care of knee flexion at swing phase. Without a proper selection of stiffness and damping coefficient for both the springs, the knee may be subjected to jerk during flexion, which may give rise to discomfort to the user and consequently, he/she may fall during walking. This study aims to ensure smooth knee operation in both stance phase as well as swing phase by assigning the proper spring stiffness and damping coefficient for both the springs. The responsibility is given to a non-traditional optimization tool, namely particle swarm optimization (PSO). The optimization is carried out using a co-simulation approach between Matlab and ADAMS. The aim of PSO (run in Matlab) is to minimize both the frequency as well as amplitude of the jerk by finding a suitable set of design variables, that is, spring stiffness and damping coefficient of two spring-damper systems.
Design and Evaluation of the Fresnel-Lens Based Solar Concentrator System Through a Statistical-Algorithmic Approach
Authors: Qandil Hassan , Zhao Weihuan
Published: January 2019

A novel non-imaging Fresnel-lens-based solar concentrator-receiver system has been investigated to achieve high-efficiency photon and heat outputs with minimized effect of chromatic aberrations. Two types of non-imaging Fresnel lenses, a spot-flat lens and a dome-shaped lens, are designed through a statistical algorithm incorporated in MATLAB. The algorithm optimizes the lens design via a statistical ray-tracing methodology of the incident light, considering the chromatic aberration of solar spectrum, the lens-receiver spacing and aperture sizes, and the optimum number of prism grooves. An equal-groove-width of the Poly-methyl-methacrylate (PMMA) prisms is adopted in the model. The main target is to maximize ray intensity on the receiver’s aperture, and therefore, achieve the highest possible heat flux and output concentration temperature. The algorithm outputs prism and system geometries of the Fresnel-lens concentrator. The lenses coupled with solar receivers are simulated by COMSOL Multiphysics. It combines both optical and thermal analyses for the lens and receiver to study the optimum lens structure for high solar flux output. The optimized solar concentrator-receiver system can be applied to various devices which require high temperature inputs, such as concentrated photovoltaics (CPV), high-temperature stirling engine, etc.
Simulation and Optimization of Airframe Assembly Process
Authors: Lupuleac Sergey , Zaitseva Nadezhda , Stefanova Maria , Berezin Sergey , Shinder Julia , Petukhova Margarita , Bonhomme Elodie
Published: January 2019

An approach for simulating the assembly process where compliant airframe parts are being joined by riveting is presented. The foundation of this approach is the mathematical model based on the reduction of the corresponding contact problem to a Quadratic Programming (QP) problem. The use of efficient QP algorithms enables mass contact problem solving on refined grids, which is needed for variation analysis and simulation as well as for the consequent assembly process optimization. To perform variation simulation, the initial gap between the parts is assumed to be stochastic and a cloud of such gaps is generated based on statistical analysis of the available measurements. The developed approach is illustrated with two examples, simulation of A350-900 wing-to-fuselage joining and optimization of A320 wing box assembly. New contact quality measures are discussed.
EHSA Primary Flight Controls Seals Wear Degradation Model
Authors: Bertolino Antonio C. , Gentile Rocco , Jacazio Giovanni , Marino Francesco , Sorli Massimo
Published: January 2019

Seals are widely used in hydraulic power systems to prevent fluid leakages. However, several types of degradation can decrease the performance of these components such as wear, which induces changes in the geometry of the cross-section area, influencing their sealing capability. Over the years, their behaviour has been primarily investigated with several theoretical and experimental researches. All these valuable results can be considered as a starting point for further investigations on the interaction between seals and the complete hydraulic equipment and on the root of seals degradation.

This article proposes a physical model of performance degradation acting on dynamic seals of an electro-hydraulic servo-actuator (EHSA) ram for primary flight controls. In this article, a dynamic non-linear seals degradation model has been developed, based on the Hart-Smith hyperelasticity model, which physically describes the stress and strain of “rubber-like” materials. Similarly, wearing has been assessment by using the Archard’s equation. Furthermore, different operating temperatures have been considered to analyze the effect on seals performances.

The integration between the mentioned seals degradation model and the high-fidelity model of the complete EHSA allows to evaluate the influence of various wear levels on the actuator behaviour. This research activity is inserted into a more extensive project of Prognostic and Health Management (PHM) of EHSAs. The results of the proposed simulations reveal how the performance of an EHSA can be affected by seals degradations.
Herschel-Bulkley Fluid Flow Characteristics in a Duct With an Obstacle
Authors: Ashrafi Nariman , Sadeghi Ali , Chegini Armin , Shafahi Mehdi
Published: January 2019

This study is focused on the flow of the shear thinning and shear thickening fluids of Herschel-Bulkley type past a partial vertical wall in between the plates. Upon numerically solving the continuity and momentum equations the flow is analyzed throughout the domain using a finite volume scheme. The shear stress at the wall together with velocity distribution are evaluated and compared to experimental results for several values of Herschel-Bulkley coefficients for fluidity and flow behavior index. Dynamic viscosity and other flow variables are calculated throughout the flow domain.
Development of Novel Compact Compression Specimen for Matrix Compression Damage Initiation and Propagation Behavior in Fiber Reinforced Composites
Authors: McKinley Tim A. , Carpenter Kevin T. , Parmigiani John P.
Published: January 2019

Robust design and analysis of carbon fiber reinforced polymers (CFRP) mandates a thorough understanding of the onset and propagation of damaging mechanisms. Damage can manifest from fiber tension, fiber compression, matrix tension, and matrix compression. Of these damage forms, matrix compression has seen the least attention. Previous work has developed experimental specimens that enabled characterization of the onset and propagation of matrix compression damage. However, if high performance composite materials are used complications can arise when the matrix compression strength (σMC) exceeds the matrix tension strength (σMT). When the σMC/σMT ratio is greater than 2, compact compression (CC) specimens can exhibit matrix tension damage before the onset of matrix compression damage. The onset of matrix tension damage prevents proper characterization of matrix compression damage mechanisms. This paper presents the development of a novel stepped compact compression specimen. The reduced thickness of the stepped region allows significant matrix-compression damage to occur prior to tensile failure. Specimens comprised of 90° plies were fabricated using either a machined taper or a layering process. Both methods were successful however variability in machining generated substantial inconsistency and layering was found to be superior.
Control of Continuous Polymer Compounding Fuse Filament Modeling
Authors: Armstrong Connor D. , Carlacci Thomas , Bigio David
Published: January 2019

Controlled processing of carbon microfiber (CMF) reinforced polymers widens control of material properties of fabricated parts. Continuous transfer from compounding to Fused Filament Modeling (FFM) platform brings this advantage to additive manufacturing. CMF reinforced composites are compounded using a co-rotating twin screw extrusion machine (CoTSE). Controlled, direct transfer from the CoTSE to FFM is accomplished using a mechanical system comprised of interconnected feedback control subsystems. Controlled transfer of CMF reinforced composite polymers is studied over a selected range of temperatures, volumetric flow conditions, and microfiber weight fractions using the system. Characteristics of the produced materials are discussed with respect to CMF weight fractions and processing conditions.
Use of Ultrasonic and Audio Signals to Monitor Temperature in Stratospheric Balloons
Authors: Jones Matthew C. , Ash Jason T. , Tolle Charles R. , Smith Michael
Published: January 2019

For gas temperature measurements in stratospheric balloons, traditional methods of measuring gas temperature do not work well due to radiant heating and insufficient heat transfer. To measure the gas temperature several methods of acoustic temperature measurement are being developed. One of these methods is the pitch catch method. A perceived distance pitch catch method using an ultrasonic distance sensor was proposed and tested. However, at low pressures the density of air is too low to allow sound to propagate well. This means that at a certain pressure, the ultrasonic distance sensor will not receive a reflected sound with sufficient amplitude to calculate the apparent distance accurately. Tests were conducted in a high altitude chamber to determine the accuracy of temperature measurements and the fail pressure. It was determined that the optimum configuration for this device would not allow it to function at a sufficient altitude nor give the temperature accuracy required. An alternative timing method using a piezo speaker, electret microphone, and time of flight measurements was explored. The timing method achieved a detectable signal down to 1.0kPa. Further work is being done on the timing method to increase the accuracy of the device.