bluuebunny/crossref_metadata_2025 huggingface dataset:
SPECIAL ISSUE ON INNOVATION AND APPLICATION OF MECHANICAL ENGINEERING GUEST EDITORIAL
Authors: Hsieh Wen-Hsiang
Published: April 2018

Machines make all industrial artifacts and mechanical products in the world. In this 21th century, people enjoy mechanical products that made lives well and convenient. However, creating a useful mechanical product mainly relies on academic development and technology innovation especially in the field of mechanical engineering. This special issue focuses on the innovation and application of mechanical engineering, which covers a wide range of fundamental studies, technical innovation, and industrial applications by applying the knowledge of mechanical-related approaches, processes and techniques. It presents 33 selected papers (Part 1) from the 3rd International Conference on Engineering and Technology Innovation (ICETI 2014) which was held from October 31 to November 4, 2014, in Kenting, Taiwan. These selected papers underwent a complete Transactions of the Canadian Society for Mechanical Engineering peer-review. Acceptance in this special issue was based on completion of the reviewers recommended and mandatory changes and final examination by the Guest Editor. We thank all of the authors who have submitted their work for publication in this special issue. We are also grateful to the many reviewers that provided their time and expertise in providing valuable peer review. Special thanks also go to Professor Paul J. Zsombor-Murray, Editor of Transactions of the Canadian Society for Mechanical Engineering, who had the foresight to support a special issue in this research area. This special issue is expected to be a core issue for academic researches and industrial engineers in the mechanical engineering field.
ADAPTIVE SLIDING-MODE CONTROL: SIMPLEX-TYPE METHOD
Authors: Chen Ta-Tau
Published: April 2018

The simplex method is easy and brief for designing the sliding mode, but it also has some disadvantages. Since the control vectors are constant, the chattering phenomenon also occurs when switching control takes place in simplex-type SMC scheme. Hence, we make few modifications to the simplex method that form an irregular simplex such that it improves the choice of simplex control vector and chattering phenomenon. The irregular simplex is obtained by an adaptive control law. The stabilization of a nonlinear multi-input system by using adaptive control based on simplex-type sliding-mode control philosophy is examined in this paper. The adaptive law and stabilization theorem are proposed and proved. The simulation results demonstrate that the simplex-type adaptive sliding-mode control proposed in this paper is a good solution to the chattering problem in the simplex sliding-mode control.
DESIGN AND ANALYSIS OF CAM MECHANISM WITH TRANSLATING FOLLOWER HAVING DOUBLE ROLLERS
Authors: Hsieh Jung-Fa
Published: April 2018

The pressure angle is one of the primary considerations in designing a cam mechanism since an inappropriate angle may cause excessive sliding loads on the follower. This paper presents a simple yet straightforward method for the design and analysis of a cam mechanism with a translating follower having double rollers. In the proposed approach, conjugate surface theory is employed to derive a kinematic model of the cam mechanism. Analytical expressions for the pressure angle and principal curvatures of the cam profile are then derived. The validity of the analytical expressions is confirmed by machining a designed cam using a 3-axis CNC machine tool.
THE DESIGN AND MESHING EFFICIENCY ANALYSIS OF HELICAL SPUR GEAR REDUCER WITH SINGLE GEAR PAIR FOR ELECTRIC SCOOTERS
Authors: Hsieh Long-Chang , Chen Tzu-Hsia , Tang Hsiu-Chen
Published: April 2018

To achieve reduced costs and energy conservation, this paper proposes non-standard helical spur gear reducer with one gear pair (having reduction ratio 19.25) to be the gear reducer for electric scooter. This paper also focuses on the meshing efficiency analysis of non-standard helical spur gear pair. According to Buckingham’s research, the theoretical meshing efficiency formula of non-standard helical spur gear pair is derived. Three design cases of non-standard helical spur gear pair (4, 77) are proposed as examples for analyzing their meshing efficiencies at widely rotation speed range. The theoretical meshing efficiencies for the helical spur gear pair (4, 77) are between 96.47–99.26%. Its best meshing efficiency occurs at 800–1000 rpm of pinion. The meshing efficiencies of these three design cases are almost same, and their differences are less than 0.5%. Considering the root strength of pinion, Cases II and III are better than Case I.
PIRAA: DEVELOPMENT OF AN INJECTION MOLDING MACHINE MANUFACTURING MONITORING SYSTEM BASED ON PRODUCTION INFORMATION RETRIEVAL AGENT ARCHITECTURE
Authors: Chen Shang-Liang , Lin You-Chen , Chen Yun-Yao , Wang Sin-Ru
Published: April 2018

Production information retrieval is an important issue for manufacturing industries. Effective data transmission and retrieval mechanism with data protection is an urgent research topic. Therefore, a socket information retrieval mechanism and agent services for information retrieval on the basis of injection molding machines is proposed in this research and is addressed as Production Information Retrieval Agent Architecture (PIRAA). The proposed agent adapted a customized packet format for client-server connection communication and sent process parameters back to a production process database. Using the experimental results, a cloud-based platform was implemented based on injection molding machines. The results show the PIRAA framework can be used for developing cloud-based platforms in a stabilized and remarkable way.
MINIATURE FLUID DYNAMIC BEARING WITH IMPROVED LOAD CAPACITY
Authors: Liu Chien-Sheng , Lee Min-Kai , Chuo Ying-Chi
Published: April 2018

In this paper a novel design is proposed to improve the load capacity of fluid dynamic bearing (FDB) for miniature spindle motors and small-form-factor data storage applications. In contrast to conventional miniature FDB with two sets of herringbone grooves on its inner surface, the proposed miniature FDB comprises another one set of herringbone grooves on its outer surface. The proposed miniature FDB is verified numerically utilizing commercial software Advanced Rotating Machinery Dynamics (ARMD). The simulation results show that compared to the conventional miniature FDB, the proposed miniature FDB can obviously improve the load capacity of the bearing system. Overall, the results presented in this study show that the proposed miniature FDB provides another solution for miniature spindle motor applications.
OPTIMIZATION OF INFLUENTIAL PROCESS PARAMETERS ON THE DEEP DRAWING OF ALUMINIUM 6061 SHEET USING TAGUCHI AND FINITE ELEMENT METHOD
Authors: Nguyen Van Quang , Ramamurthy Balamurugan , Lin Jau-Wen
Published: April 2018

The plastic deformation behavior of axis symmetric aluminium 6061 cups was determined by analyzing the four important deep drawing process parameters, namely blank temperature, die edge radius, blank holder force and friction coefficient. Taguchi techniques along with finite element method (FEM) were used to determine the importance of process parameters. The Taguchi method was used to analyze the influence of each process parameter. From the deformation result and analysis of variance (ANOVA), it was determined that the temperature of the blank has a major influence on the deformation characteristic of aluminium 6061 sheets followed by die edge radius, coefficient of friction, and blank holder force. The optimum levels of the four factors in determining the deformed cup heights are found to be blank temperature of 450°C, die edge radius of 14 mm, coefficient of friction of 0.60 and blank holder force of 9 KN.
STUDY ON THE DESIGN ADAPTIVE RECURRENT WAVELET NEURAL NETWORK CONTROL OF AN AUTO TIG WELD SYSTEM
Authors: Lee Yung-Lung , Hsu Shou-Jen , Chen Yen-Bin
Published: April 2018

An adaptive recurrent wavelet neural network control (WNN) method was developed to improve quality and system performance in welded aluminum alloy vacuum chamber production. Tests were carried out using a multi-gun automatic system. Using WNN, this research is meant to overcome weld inconsistencies and faults that cause leaks and are due to variability of skill and performance among human operators. By using this method to control welding current, wire feed rate, argon flow rate and welding speed, desired results are hopefully achieved.
A GENERAL CAD/CAM MODEL FOR APT-LIKE ROTARY MILLING CUTTERS
Authors: Wu Chang-Tzuoh , Liu Nien-Te
Published: April 2018

This paper presents a general mathematical model for NC-machining an APT-LIKE rotating cutter. The design model of cutting-edge and helical groove is also developed by using the principles of differential geometry and kinematics. Based on the envelope condition, approaches for solving the inverse problems that are related to the manufacturing models are also presented. The velocities of the cutter in the radial and axial directions are then determined based on the gouging avoidance of grooves. The results of the numerical experiment indicate that the proposed systematic design method by using 2-axis NC machine setup is feasible and reliable.
THE STUDY OF AN INNOVATIVE HEAT REMOVAL MODEL OF THE ALUMINUM-ACETONE FLAT PLATE HEAT PIPE ON HIGH POWER LEDS
Authors: Cheng Po-Jen , Lin David T.W. , Liu Wu-Man , Hsieh Jui-Ching , Wang Chi-Chang
Published: April 2018

It is well known that heat generation will be harmful to high power LEDs. It is hardly effectively dissipated and results in a serious problem in the luminous efficiency. The most important issue in LED research is to find a potential design of heat removal. The purpose of this study is to design the LEDs combined with the cooling module of the aluminum-acetone flat plate heat pipe by the experimental and numerical simulation for obtaining high efficiency in heat removal. The high power LEDs with and without heat pipe cooling module are compared. The numerical simulation is built and agrees with the experiment. The heat removal efficiency of the cooling module reaches 92.09% and drops the junction temperature of LED about 36°C. This cooling module has proven to be effective in solving the heat concentration problems associated with the LED chips. In short, the phase change cooling module will apply on the electronic component of high heat concentration for more effective cooling method.
DESIGN AND ANALYSIS OF CAM MECHANISM WITH NEGATIVE RADIUS ROLLER-FOLLOWER
Authors: Hsieh Jung-Fa
Published: April 2018

This paper presents a simple method for the design and analysis of a cam mechanism with a negative radius roller-follower. In the proposed approach, conjugate surface theory is employed to derive a kinematic model of the cam mechanism. Analytical expressions for the pressure angle and principal curvatures of the cam profile are then derived. Finally, analytical expressions for the angular velocity and angular acceleration of the roller are derived. The validity of the proposed design methodology is demonstrated by machining a cam mechanism having a negative radius roller-follower with a radius of 100 mm.
DESIGN OF A PITCH-ROLL JOYSTICK BASED ON A THREE-LOBE SPHERICAL CAM MECHANISM
Authors: Saha Debal , Angeles Jorge , Kövecses Jozsef
Published: April 2018

A pitch-roll joystick based on a spherical cam mechanism is proposed that can be implemented as a haptics device. Spherical cams can replace the bevel gears that are conventionally used in transmission mechanisms involving shafts with intersecting axes to achieve lower backlash, lower frictional losses and higher stiffness. Such a spherical cam mechanism is essentially composed of multi-lobe-cams and conical rollers. Undercutting is a deterrent to the generation of smooth cam surfaces, which calls for the synthesis of a singularity-free spherical cam profile. The issues of high pressure angle and high contact ratio are addressed by means of a multilobe cam. The design of the cam profile and the assembly of the joystick are described. The criteria for the selection of the numbers of lobes and rollers are also explained.
DESIGN OF A VISION GUIDED MECHATRONIC QUADROTOR SYSTEM USING DESIGN FOR CONTROL METHODOLOGY
Authors: Mohebbi Abolfazl , Achiche Sofiane , Baron Luc
Published: April 2018

Designing mechatronic systems is known to be both a very complex and tedious process. This complexity is due to the high number of system components, their multi-physical aspects, the couplings between different engineering domains and the interacting and/or conflicting design objectives. Due to this inherent complexity and the dynamic coupling between subsystems of mechatronic systems, a systematic and multi-objective design approach is needed to replace the traditionally used sequential design methods. The traditional approaches usually lead to functional but non optimal designs solutions. In this paper, and based on an integrated and concurrent design approach called “Design-for-Control” (DFC), a quadrotor UAV equipped with a stereo visual servoing system is used as a case study. After presenting the dynamics and the control model of the Quadrotor UAV and its visual servoing system, the design process has been performed in four iterations and as expected, the control performance of the system has been significantly improved after finishing the final design iteration.
DESIGN AND TESTING OF A NEW WATER SUPPLY DEVICE
Authors: Cui Cong , Duan Xili , Ren Weiyan , Hu Yulu
Published: April 2018

When water is supplied from pressurized pipelines, the high pressure often causes waste of water by splashing and unnecessarily high flow rates. In this research, an innovative new water supply device is designed to overcome this problem. In this device water is supplied in the form of overflow by automatically adjusting water pressure at the inlet. This paper presents the mechanical design of the new faucet and explains how it operates in sensor mode and bypass mode. Experimental results show that the new design achieves near-zero outflow pressure and can still provide rapid water supply when required.
OPTIMIZATION OF MODIFIED WATT’S LINKAGE FOR AN APPROXIMATELY LONG STRAIGHT PATH WITHIN LIMITED DIMENSION
Authors: Wu Jun , Fan Shaowei , Jin Minghe , Liu Hong
Published: April 2018

This paper presents an optimal method of aiming for an approximately straight path of the Modified Watt’s Linkage (MWL) within limited dimension. A modification to the Watt’s linkage and the corresponding condition are introduced, followed by the kinematic synthesis. The path generation based on the modification considering constraints from practical application is provided. Genetic algorithm is utilized to perform the constrained optimization. The centrosymmetric property of the MWL is considered in the synthesis process. Ideal parameters of the mechanism are achieved to demonstrate the effectiveness of the proposed method.
A NEW TYPE OF INCREMENTAL BENDING METHOD FOR COMPLICATED CURVED SHEET METAL
Authors: Li Jiuhua , Dang Xiaobing , He Kai , Zuo Qiyang , Du Ruxu
Published: April 2018

A new type of incremental bending process for complicated curved sheet metal is proposed in the paper. The blank sheet is bended incrementally step by step. To validate the forming process, an incremental bending prototype is designed and manufactured, which was composed of a 3-DOF working table, a flexible supporting system and a 3D scanning system. The forming trajectory based on the theory of the minimum energy is planned according to the designed model of the sheet metal. Several experiments are carried out and the designed part is manufactured, which validated the proposed incremental forming method was successful.
EXPERIMENTAL STUDY ON TUBE JAMMING THROUGH A WEDGE-SHAPED HOPPER
Authors: Chang Chih-Yuan , Chen Wei-Zhong
Published: April 2018

A wedge-shaped hopper is frequently utilized as a tube feeder in the electric heater process. When falling from a wedge-shaped hopper, the tubes often form an arch near the outlet and stop the feeding process since a pile of tubes pass through a small hopper outlet one by one. This research aims to investigate the effect of process factors on the tube feeding process by applying Taguchi’s method and to design a wedge-shaped hopper that never jams. Chosen process factors are the wall angle of the hopper, outlet width of the hopper, number of test tubes, vibration strength of the vibrators and tube materials. Experimental results show that a large wall angle, a wide hopper outlet, a few tubes and a weak vibration are optimal settings. The wall angle and the outlet width of the hopper are more influential to reduce the jamming for all tube materials. A hopper that hardly jams can be designed by using optimum conditions.
CALCULATION OF ADDITIONAL AXIAL FORCE OF ANGULAR-CONTACT BALL BEARINGS IN ROTOR SYSTEM
Authors: Ye Zhenhuan , Liu Zhansheng , Wang Liqin
Published: April 2018

Based on a loading-deformation relationship of bearing elements and the coordination of displacement between bearings in the rotor system, a model for calculating the additional axial force of angular-contact ball bearings in a single-rotor system is established. Nonlinear equations of this model are solved through the Rapid Descent method and Newton-Raphson method. The simulation results which are based on Gupta’s example verify that both the model and solving methods in this paper are reliable. A pair of 276927NK1W1(H) angular-contact ball bearings in symmetry in the single-rotor system is used as the example, calculation results of the additional axial force of bearings from the model in this paper and from the ISO method are compared and the influence of bearing geometry parameters and working conditions on the additional axial force is further studied. This model and its conclusions could provide the basic data and reference for analyzing the carrying ability and dynamic properties of rolling bearings.
PULSED ELECTROCHEMICAL MICRO MACHINING OF INVAR (FE-NI) FILM USING AN ELECTRODE ARRAY
Authors: Chun Kwang-Ho , Choi Seung-Geon , Lee Eun-Sang
Published: April 2018

Recently, invar (Fe-Ni) material has been applied to OLED shadow masks due to its thermal change characteristics and thermal expansion coefficient. The most widely used manufacturing methods for invar are etching and laser machining, but they have problems like non-machined areas generated by etching and surface burning in laser machining. For this reason, an alternative machining method is necessary. In this study, pulsed electrochemical machining (PECM) has been applied to fabricate an OLED shadow mask. PECM is a highly promising technology for shadow mask manufacturing because it can produce micro-scale and complex tapered holes in one process. A pilot experiment was carried out to find a suitable electrolyte for invar film, and an array of coated Ti electrodes was used to fabricate micro holes.
AN INVESTIGATION OF FORGING STREAM LINE AND TOOL DESIGN ON MULTI-STAGE COLD FORMING OF A LONG CIRCULAR PIPE PART
Authors: Shih Ching-Wei , Tzou Gow-Yi , Chang Kao-Hua
Published: April 2018

The study aims to explore the reasons for why the fracture defects in the forging of a long circular pipe part occurred. Besides, the tool design has been proposed to eliminate the fracture defects. The flow direction, the velocity, the effective stress, the effective strain, the damage value, and so on, can be observed by using the point tracking function in the commercial simulation software. Moreover, the forging stream line occurring in the work-piece formation based on the simulation software is compared with that in the real product in order to understand the reasons for the fracture. The tool designs are modified accordingly, and the simulation software is used to confirm the acceptance of tool designs. Finally, appropriate forging has been performed to as per product requirements.
EFFECTS OF SURFACE FORCES ON SQUEEZE EHL MOTION BETWEEN ELASTIC BALL AND ELASTIC COATED SURFACE
Authors: Chu Li-Ming , Lin Jaw-Ren , Hsu Hsiang-Chen , Chang Yuh-Ping
Published: April 2018

The effects of surface forces (SF) and coated layers (CL) on pure squeeze elastohydrodynamic lubrication (EHL) motion of circular contacts are explored under constant load condition by using the finite difference method (FDM) and the Gauss–Seidel iteration method. The transient pressure profiles, surface force, film shapes, and elastic deformation during the pure squeeze process under various operating conditions in the TFEHL regime are discussed. The simulation results reveal that the difference between SFEHL model and EHL model is apparent as the film thickness is thinner than 5 nm. The oscillation phenomena in pressure and film thickness come mainly from the action of solvation forces. At contact region, the greater elastic modulus and smaller coating thicknesses, the greater pressure distribution, and the smaller film thickness. The film thicknesses are found reverse at outside the contact zone. At the exit region, i.e. the minimum film thickness region, it is valid that the greater the elastic modulus and the smaller the coating thicknesses, the greater the solvation pressure distribution. The effects of surface forces become significant as the film thickness becomes thinner.
CALCULATION OF OIL TANK VOLUME AND REPORT GENERATION SYSTEM WITH TRIM AND LIST CORRECTIONS
Authors: Hu Ming-Sen , Tao Chia-Rei
Published: April 2018

The capacity of ship’s oil tanks is usually designed as a tabled form in order to obtain oil volumes by using the measured ullage heights. However, the tank walls easily deform or distort due to long-term heavy loading. This phenomenon may cause serious errors that the carrying capacity in oil tanker does not match with the values of the tabled form. In this paper, we perform an oil tank volume calibration project that aims to develop a tank volume calculation and report a generation software with trim and list corrections. The current internal specification for each tank is measured first, and then all specification data measured can be input to this software system to calculate each tank’s volume. These calculated results will be verified by actual delivery volume tests. This software system has been applied to the Der-Yun Oil Tanker of CPC Corp. The result shows that the overall error of calibrated volume for all tanks is under 0.1%. It is proved that this system highly improves the correctness of the vessel’s carrying capacity.
ESTABLISHMENT OF DYNAMIC EQUATIONS FOR DAMPED SYSTEMS BASED ON QUASI-VARIATIONAL PRINCIPLES
Authors: Pan Yuhua , Wang Yuanfeng , Su Li
Published: April 2018

In this paper, quasi-variational principles for non-conservative damped systems are studied. A Hamiltontype quasi-variational principle for non-conservative systems in analytical mechanics and a quasi-variational principle of potential energy in non-conservative elastodynamics systems are proposed in simplified forms respectively, by using the direct variational integral method. On the basis of the standard linear solid model for viscoelastic materials, the dynamic equations of exponentially damped systems are established through the proposed quasi-variational principles. A distinction between the internal damping described by exponential damping and the external damping described by viscous one in a vibrating structure is according to different physical mechanisms, which gives some indication of the correct mechanism of damping.
RESEARCH ON THE SELF-SYNCHRONOUS VIBRATION OF FATIGUE LOADING TESTS FOR WIND TURBINE BLADES
Authors: Xuemei Huang , Lei’an Zhang , Liming Tao , Xiuting Wei
Published: April 2018

To carry on fatigue loading tests for wind turbine blades accurately, the self-synchronous vibration mechanism of loading system was investigated. Firstly, the mathematical model of vibration was deduced based on LaGrange Equation, thus the influence factors of self-synchronous vibration could be obtained. Then to study the influencing rules of the initial phase difference between loading equipment and blade, a simulating model was constructed to carry on the numerical simulation and it was found that when the driving frequency of the loading equipment was the same as the natural frequency of the blade, a different initial phase separation would generate different effect on self-synchronous vibration. Finally, an on-site fatigue test system was established to verify the accuracy of mathematical and simulation model mentioned above. It could be concluded that the test results were consistent with the simulating result. The research on the self-synchronous vibration performance of loading system for blade could supply a theory support for the sequent control of blade’s fatigue tests precisely.
DESIGN OF THE TRANSMISSION MECHANISM USED IN A MULTIPOINT MORTISE LOCK
Authors: Huang Hsing-Hui , Lin Yi-Ming
Published: April 2018

A multipoint lock is a useful lock which can provide more security and is convenient for the user. One of the aims of this article is to study how a multipoint lock is designed systematically by utilizing a mortise lock. Based on a systematic design methodology, the concepts and the atlas of designs are synthesized systematically. A feasible mechanism is further chosen for detailed design. The computer simulation is developed and the basic stress analysis is also constructed for verifying the design results. Finally, the prototype is also built. The results of this study provide a valuable reference for the design and analysis of a mortise lock’s mechanism.
STUDY ON MICRO CONTACT CHARACTERISTICS OF JOINT SURFACE BASED ON A FRACTAL THEORY
Authors: Wang Lihua , Wang Pengcheng , Yang Zu , He Yusong
Published: April 2018

In order to understand the microscopic mechanism of the joint surface, simulations of three-dimensional microscopic topography of the joint surface are done based on the fractal theory. Further, the three-dimensional microscopic surface contact models of the joint surface are designed using the fractal simulation surface topography. Then, the contact simulation analyses are carried out using finite element method and the microscopic elasticity and elastic-plastic contact characteristics between the three-dimensional microscopic surfaces are studied. The research results showed that the displacement along normal direction, contact area, and contact pressure of the joint surface increase nonlinearly with an increase in the contact load and vary with the roughness of the joint surfaces. This study provides a theoretical basis for the further research on the microscopic mechanism of the joint surface.
The effect of the number of degrees of kinematic redundancy on the actuation forces of a planar parallel manipulator
Authors: Lee Aiden , Boudreau Roger
Published: April 2018

This paper proposes a two-step optimization procedure for resolving the actuation forces of a kinematically redundant planar parallel manipulator following a specified trajectory. Simulation results compare the performance of the manipulator when different degrees of kinematic redundancy are used. It is seen that the required forces are generally lower when there are more degrees of kinematic redundancy; however, more mechanical energy is required. In some cases, fewer degrees of kinematic redundancy can produce similar results from a force point of view, while requiring less energy. Furthermore, the importance of correctly choosing an initial configuration is presented. The proposed method finds an optimal initial configuration by considering a performance index along the entire trajectory. The evolution of the singularity loci as the manipulator moves along the trajectory demonstrates why certain initial configurations should not be used, even if they are optimal at the initial pose.
Feedforward control for underactuated bipedal walking on varying compliant slopes
Authors: Yao Daojin , He Siyu , Wu Yao , Xiao Xiaohui , Wang Yang
Published: April 2018

In this paper, a feedforward control strategy is proposed to enable stable underactuated bipedal walking on varying compliant slopes with a known inclination angle, to handle the variation in natural environments. First, spring–damper units were employed in the horizontal and vertical directions to model the compliant ground, which is described as a rigid kinematic chain coupled with a spring–damper system. Second, a new definition of stable underactuated bipedal walking, based on walking speed, was proposed. Stable walking is achieved by adjusting the velocity of the biped’s center of mass (CoM) within limits that have been proven to allow at least one walking cycle. The proposed feedforward control strategy was based on the motion state of a robot’s CoM, using the new definition of stability and inspired by the gait characteristics of human walking on varying slopes. Speed control is realized by adjusting the displacement of the CoM with the change of slope to achieve stable walking. Finally, simulations were conducted to validate the proposed controller. The simulation results demonstrate that stable walking is achieved on varying compliant slopes by implementing the proposed control strategy.
Wake measurements of oscillating supercritical airfoil in compressible flow
Authors: Boroumand Behnaz Beheshti , Mani Mahmoud
Published: April 2018

Boundary layer and wake behaviors are strongly affected by airfoil motion. Moreover, parameters like body oscillation frequency, oscillation type, Mach number, and angle of attack play main roles in wake characteristics. In this research, both static and dynamic tests were carried out in a tri-sonic wind tunnel to study wake profiles experimentally by hot wire anemometry. All data were recorded at a free stream Mach number of 0.4. Quarter-length and half-length of chord were also considered as downstream distances from the trailing edge in pitching motions of mean angle of attack of −0.4°. Frequencies of 3 Hz and 6 Hz with amplitude of 3° were chosen as oscillation parameters. Voltages at hot wire outputs were measured and analyzed qualitatively and statistically with root-mean-square, correlation, mean value distribution, time history, and frequency. Flow parameters were obtained by computational studies under similar experimental test conditions. The wake characteristics obtained from numerical and experimental methods were compared.
Synchronization of distributed power grids with the external loading system
Authors: Wei Duqu , Mei Chuncao
Published: April 2018

In this paper, the synchronization between spatially distributed power plants and their supported consumers is studied, where the case of Kuramoto-like model power grids connected to an external permanent magnet synchronous motor (PMSM) is taken as an example. We focus on the dependence of the synchronization on the coupling coefficient. To quantitatively study the synchronization degree, we introduce the order parameter and the frequency deviation to measure the synchronization of the coupled system. It is found that as the external coupling coefficient is increased, the distributed power grids and the loading system become more and more synchronized in space, and the complete synchronization appears at a particular value of external coupling coefficient. Our results may provide a useful tip for analyzing the synchronous ability of distributed power grids.
Orders on magmas and computability theory
Authors: Ha Trang , Harizanov Valentina
Published: April 2018

We investigate algebraic and computability-theoretic properties of orderable magmas. A magma is an algebraic structure with a single binary operation. A right order on a magma is a linear ordering of its domain, which is right-invariant with respect to the magma operation. We use tools of computability theory to investigate Turing complexity of orders on computable orderable magmas. A magma is computable if it is finite, or if its domain can be identified with the set of natural numbers and the magma operation is computable. Interesting orderable magmas that are not even associative come from knot theory.
Parainjectivity, paraprojectivity and artinian principal ideal rings
Authors: Alvarado-García Alejandro , Cejudo-Castilla César , Vilchis-Montalvo Ivan Fernando
Published: April 2018

In this work, we introduce the concepts of parainjectivity and paraprojectivity. We give some basic properties about them and we obtain some characterizations of artinian principal ideal rings.
On S-GCD domains
Authors: Anderson D. D. , Hamed Ahmed , Zafrullah Muhammad
Published: April 2018

Let [Formula: see text] be a multiplicative set in an integral domain [Formula: see text]. A nonzero ideal [Formula: see text] of [Formula: see text] is said to be [Formula: see text]-[Formula: see text]-principal if there exist an [Formula: see text] and [Formula: see text] such that [Formula: see text]. Call [Formula: see text] an [Formula: see text]-GCD domain if each finitely generated nonzero ideal of [Formula: see text] is [Formula: see text]-[Formula: see text]-principal. This notion was introduced in [A. Hamed and S. Hizem, On the class group and [Formula: see text]-class group of formal power series rings, J. Pure Appl. Algebra 221 (2017) 2869–2879]. One aim of this paper is to characterize [Formula: see text]-GCD domains, giving several equivalent conditions and showing that if [Formula: see text] is an [Formula: see text]-GCD domain then [Formula: see text] is a GCD domain but not conversely. Also we prove that if [Formula: see text] is an [Formula: see text]-GCD [Formula: see text]-Noetherian domain such that every prime [Formula: see text]-ideal disjoint from [Formula: see text] is a [Formula: see text]-ideal, then [Formula: see text] is [Formula: see text]-factorial and we give an example of an [Formula: see text]-GCD [Formula: see text]-Noetherian domain which is not [Formula: see text]-factorial. We also consider polynomial and power series extensions of [Formula: see text]-GCD domains. We call [Formula: see text] a sublocally [Formula: see text]-GCD domain if [Formula: see text] is a [Formula: see text]-GCD domain for every non-unit [Formula: see text] and show, among other things, that a non-quasilocal sublocally [Formula: see text]-GCD domain is a generalized GCD domain (i.e. for all [Formula: see text] is invertible).
Co-maximal graphs of two generator groups
Authors: Miraftab B. , Nikandish R.
Published: April 2018

Let [Formula: see text] be a group. The co-maximal graph of [Formula: see text], denoted by [Formula: see text], is a graph whose vertices are nontrivial elements of [Formula: see text] and two distinct vertices [Formula: see text] and [Formula: see text] are adjacent in [Formula: see text] if and only if [Formula: see text]. In this paper, we study some connections between the graph-theoretic properties of this graph and some algebraic properties of groups. For instance, we characterized all groups whose co-maximal graphs are connected and we show that if [Formula: see text] has no isolated vertex, then [Formula: see text] is connected with diameter at most 2. Moreover, we classify all groups whose co-maximal graphs are complete. Also, some results on the clique number and chromatic number of a co-maximal graph are given. In addition, the co-maximal graphs of abelian groups are studied.
Sylow 2-subgroups of the fixed point subgroup and the solvability of finite groups
Authors: Jiang Qinhui , Chen Zhaoying , Li Kefeng
Published: April 2018

Let [Formula: see text] be a finite group which acts coprimely on finite group [Formula: see text] via automorphisms. We investigate the influence of the structural conditions of the Sylow [Formula: see text]-subgroups of the fixed point subgroup of the action, [Formula: see text], working on the non-simplicity or solvability of [Formula: see text].
Symmetries in idempotent factorizations
Authors: Khurana Anjana , Khurana Dinesh , Nielsen Pace P.
Published: April 2018

In analogy to the fact that isomorphic idempotents arise from flipped factorizations, we show that under some weak conditions, partial factorizations of the complement idempotents may also be preserved. Applying these results, we give new characterizations of exchange rings. We also show that the definition of an exchange element is left–right symmetric.
Left and right regular elements of the semigroups of transformations preserving an equivalence relation and a cross-section
Authors: Sawatraksa Nares , Namnak Chaiwat , Chinram Ronnason
Published: April 2018

Let [Formula: see text] be the semigroup of all transformations on a set [Formula: see text]. For an arbitrary equivalence relation [Formula: see text] on [Formula: see text] and a cross-section [Formula: see text] of the partition [Formula: see text] induced by [Formula: see text], let [Formula: see text] [Formula: see text] Then [Formula: see text] and [Formula: see text] are subsemigroups of [Formula: see text]. In this paper, we characterize left regular, right regular and completely regular elements of [Formula: see text] and [Formula: see text]. We also investigate conditions for which of these semigroups to be left regular, right regular and completely regular semigroups.
Salvage value and three variable Weibull deteriorating rate for non-instantaneous deteriorating items
Authors: Patel Hetal , Gor Ajay
Published: April 2018

Existing study gives ordering policy for non-instantaneous deteriorating items having three-variable Weibull distribution deterioration rate. Demand rate varies in different time interval. Before deterioration starts, demand is constant and after that it decreases exponentially with respect to time. The study considers total cost function as objective function including salvage value. Shortages are not allowed to stay in time-based competition. Results are proved theoretically and numerically. Sensitivity analysis is performed with respect to salvage value, scale parameter, shape parameter and location parameter including in deterioration rate function to show the liability of the model.
Mimicking a flow-limited human upper airway using a collapsible tube: relationships between flow patterns and pressures in a respiratory model
Authors: Zhu Kaixian , Farré Ramon , Katz Ira , Hardy Sébastien , Escourrou Pierre
Published: April 2018

The upper airway (UA) in humans is commonly modeled as a Starling resistor. However, negative effort dependence (NED) observed in some patients with obstructive sleep apnea (OSA) contradicts predictions based on the Starling resistor model in which inspiratory flow is independent of inspiratory driving pressure when flow is limited. In a respiratory bench model consisting of a collapsible tube and an active lung model (ASL5000), inspiratory flow characteristics were investigated in relation to upstream, downstream, and extra-luminal pressures (denoted as Pus, Pds, and Pout, respectively) by varying inspiratory effort (muscle pressure) from −1 to −20 cmH2O in the active lung. Pus was provided by a constant airway pressure device and varied from 4 to 20 cmH2O, and Pout was set at 10 and 15 cmH2O. Upstream resistance at onset of flow limitation and critical transmural pressure (Ptm) corresponding to opening of the UA were found to be independent of Pus, Pds, and Pout. With fixed Ptm, when Pds fell below a specific value (Pds′), inspiratory peak flow became constant and independent of Pds. NED plateau flow patterns at mid-inspiration (V̇n) were produced within the current bench setting when Pds fell below Pds′. V̇n was proportional to Pds, and the slope (ΔV̇n/ΔPds) increased linearly with Ptm. Ptm and Pds were the two final independent determinants of inspiratory flow. Our bench model closely mimics a flow-limited human UA, and the findings have implications for OSA treatment and research, especially for bench-testing auto-titrating devices in a more physiological way.

NEW & NOTEWORTHY A respiratory model consisting of a collapsible tube was used to mimic a flow-limited human upper airway. Flow-limited breathing patterns including negative effort dependence were produced. Transmural and downstream pressures acting on the tube are the two independent determinants of the resulting inspiratory flow during flow limitation. The findings have implications for obstructive sleep apnea treatment and research, especially for bench-testing auto-titrating devices in a more physiological way.
Detection ofYersinia enterocoliticain Retail Chicken Meat, Mashhad, Iran
Authors: Sirghani Khadigeh , Zeinali Tayebeh , Jamshidi Abdollah
Published: April 2018

Poultry meat is one of the most important sources of infection ofYersiniaspp. for humans. The aim of the present study was to evaluate the incidence ofYersinia enterocoliticain chicken meat by using culture method on selective medium and confirmation by PCR assay. Also, biochemical methods were used for biotyping. A total of 100 chicken thigh meat samples were collected randomly from retail outlets in Mashhad, Iran. Samples were enriched in Peptone-Sorbitol-Bile (PSB) broth and then cultured on Cefsulodin-Irgasan-Novobiocin (CIN) agar containing antibiotics supplement. The DNA was extracted from suspected colonies ofYersiniaspp. and then PCR test using specific primers for 16S rRNA gene ofYersinia enterocoliticawas performed. In this study, 30% of chicken meat was contaminated withYersiniaspp. by culture method and 25% of chicken meat was contaminated withYersinia enterocolitica. Biotyping of isolated colonies showed that all of the isolates belonged to biotype 1A. Culture and detection ofYersiniaspp. from food samples traditionally take 4 days. Due to high accuracy and speed of PCR assay, it is a good alternative method for microbiological techniques. In conclusion, poultry meat can act as a source ofY. enterocoliticaand could be considered as a public health hazard.
Influence of TNF and IL17 Gene Polymorphisms on the Spondyloarthritis Immunopathogenesis, Regardless of HLA-B27, in a Brazilian Population
Authors: Rocha Loures Marco A. , Macedo Luciana C. , Reis Denise M. , Oliveira Camila F. , Meneguetti Jean L. , Martines Gabriela F. , Neves Janisleya S. F. , de Souza Eliana , Sell Ana M. , Visentainer Jeane E. L.
Published: April 2018

Background and Objectives. Spondyloarthritis (SpA) represents a heterogeneous group of immune-mediated inflammatory diseases that have overlapping clinical features, genetic predisposition, and pathogenic mechanisms. Hence, we investigated, through a case-control study, whether single-nucleotide polymorphisms of TNF and IL17 genes are associated with SpA, ankylosing spondylitis (AS), and psoriatic arthritis (PsA) in a mixed Brazilian population. Methods. Genotyping of TNF-308 (rs1800629), TNF-238 (rs361525), IL17A (rs2275913), IL17F (rs763780), and HLA-B27 polymorphisms was performed in 243 patients with SpA and 210 controls from Southern Brazil using SSOP-Luminex (One Lambda) and PCR-SSP assays. Results. Significant associations were confirmed between the HLA-B27 marker and SpA, AS, and PsA diseases. While TNF-308 (rs1800629) AA/GA, IL17A (rs2275913) AA/GA, and IL17F (rs763780) CC/TC genotype frequencies were associated, in the dominance inheritance model, with SpA and AS, regardless of gender, the presence of HLA-B27, TNF-238 (rs361525) GA/AA, IL17A (rs2275913) AA/GA, and IL17F (rs763780) genotypes was associated with PsA. Conclusion. In this Brazilian population, TNF and IL17 gene polymorphisms responsible for the expression of important inflammatory cytokines were associated with overall SpA, and, specifically, with AS and PsA, regardless of gender and HLA-B27. However, future larger studies with different ethnicities may be necessary to confirm these genetic associations.
Potential of Electrospun Poly(3-hydroxybutyrate)/Collagen Blends for Tissue Engineering Applications
Authors: Salvatore Luca , Carofiglio Vito Emanuele , Stufano Paolo , Bonfrate Valentina , Calò Emanuela , Scarlino Stefania , Nitti Paola , Centrone Domenico , Cascione Mariafrancesca , Leporatti Stefano , Sannino Alessandro , Demitri Christian , Madaghiele Marta
Published: April 2018

In this work, tunable nonwoven mats based on poly(3-hydroxybutyrate) (PHB) and type I collagen (Coll) were successfully produced by electrospinning. The PHB/Coll weight ratio (fixed at 100/0, 70/30, and 50/50, resp.) was found to control the morphological, thermal, mechanical, and degradation properties of the mats. Increasing collagen amounts led to larger diameters of the fibers (in the approximate range 600–900 nm), while delaying their thermal decomposition (from 245°C to 262°C). Collagen also accelerated the hydrolytic degradation of the mats upon incubation in aqueous medium at 37°C for 23 days (with final weight losses of 1%, 15%, and 23% for 100/0, 70/30, and 50/50 samples, resp.), as a result of increased mat wettability and reduced PHB crystallinity. Interestingly, 70/30 meshes were the ones displaying the lowest stiffness (~116 MPa; p<0.05 versus 100/0 and 50/50 meshes), while 50/50 samples had an elastic modulus comparable to that of 100/0 ones (~250 MPa), likely due to enhanced physical crosslinking of the collagen chains, at least at high protein amounts. All substrates were also found to allow for good viability and proliferation of murine fibroblasts, up to 6 days of culture. Collectively, the results evidenced the potential of as-spun PHB/Coll meshes for tissue engineering applications.
Effects of Astaxanthin on Miniature Pig Sperm Cryopreservation
Authors: Lee Eunjoo , Kim Daeyoung
Published: April 2018

The purpose of this study is to evaluate the effects of astaxanthin added to freezing buffer on semen parameters, total sperm oxidation stress after postthawing of boar sperm, and lipid peroxidation (LPO) which is caused by reactive oxygen species (ROS) in sperm membrane. Varying concentrations of astaxanthin (0, 10, 50, 100, and 500 μM) were used in the freezing buffer during cryopreservation to protect the DNA of thawed miniature pig sperm. Semen parameter was measured using computer-assisted sperm analysis (CASA) for sperm motility, and then ROS rate and oxidative stress of boar sperm were determined using fluorescence-activated cell sorting (FACS). Sperm motility was higher (p<0.05) in the astaxanthin group than in the control group. Sperm motility and the number of progressive motile sperm were higher (p<0.05) in the astaxanthin 500 μM group than in the control group. In ROS evaluation, the astaxanthin group had lower intracellular O2and H2O2in viable sperm. Yo-Pro-I/HE and PI/H2DCFDA staining as revealed using flow cytometry was lower in astaxanthin groups than in the other groups. As a result, we found that astaxanthin could protect the sperm plasma membrane from free radicals and LPO during boar sperm postthawing.
Sunburn as a Cause of Unexpected Neutrophilia in a Healthy Pregnant Woman
Authors: Harper Robert
Published: April 2018

Background. Neutrophilia has a broad differential diagnosis and represents a systemic response to an infection or other inflammatory pathologies. Case. A 31-year-old woman, Gravida 3, Para 2 at 28 weeks of gestation, presented to the day assessment unit following routine blood tests that showed an unexpected marked neutrophilia. The underlying cause of the neutrophilia was sunburn. The sunburn recovered and her neutrophil count spontaneously normalised. Conclusion. Clinicians can add sunburn to the broad differential diagnosis of neutrophilia.