Experimental model and analytic solution for real-time observation of vehicle’s additional steer angle

The current research of real-time observation for vehicle roll steer angle and compliance steer angle（both of them comprehensively referred as the additional steer angle in this paper） mainly employs the linear vehicle dynamic model, in which only the lateral acceleration of vehicle body is considered. The observation accuracy resorting to this method cannot meet the requirements of vehicle real-time stability control, especially under extreme driving conditions. The paper explores the solution resorting to experimental method. Firstly, a multi-body dynamic model of a passenger car is built based on the ADAMS/Car software, whose dynamic accuracy is verified by the same vehicle＇s roadway test data of steady static circular test. Based on this simulation platform, several influencing factors of additional steer angle under different driving conditions are quantitatively analyzed. Then ε-SVR algorithm is employed to build the additional steer angle prediction model, whose input vectors mainly include the sensor information of standard electronic stability control system（ESC）. The method of typical slalom tests and FMVSS 126 tests are adopted to make simulation, train model and test model＇s generalization performance. The test result shows that the influence of lateral acceleration on additional steer angle is maximal （the magnitude up to 1°）, followed by the longitudinal acceleration-deceleration and the road wave amplitude （the magnitude up to 0.3°）. Moreover, both the prediction accuracy and the calculation real-time of the model can meet the control requirements of ESC This research expands the accurate observation methods of the additional steer angle under extreme driving conditions.     

A study on the modeling and analysis of a helicopter’s occupant seat belt for crashworthiness

Abstrac  In this paper, a method of modeling a seat belt on a crew seat during a dynamic seat testing was studied. The body segments of the occupant were modeled with joints that consisted of various stiffness, damping, and friction. Three types of seat belt restraint systems were investigated and an analysis on the injury assessment of the helicopter’s crew under a drop impact was conducted. The effectiveness of the seat belt system for crashworthiness and safety was likewise evaluated. From the impact analysis results, it was determined that the head, neck, and spine of the crew body can be easily damaged in the vertical direction more than the longitudinal direction. Based on the verified model, the human body’s behavior was studied using three point restraint systems. The displacement and injury level of the 12-point restraint system was the smallest. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Young-Shin Lee received a B.S. degree in Mechanical Engi-neering from Younsei University, Korea in 1972. He received master and Ph.D. degree in Mechanical Engineering from Yonsei University, Korea in 1974 and 1980 respectively. He is currently professor and Dean of Industry Graduate School and Director of BK21 Mechatronics Group at Chungnam National University, Korea. Prof. Lee’s research interests are in area of impact mechanics, optimal design, biomechanical analysis and shell structure analysis. Jung-Hyun Lee received a B.S. degree in Mechanical Design Engineering from Chungnam Na-tional University, Korea in 2007. He received master degree in Mechanical Design Engineering from Chungnam National Uni-versity, Korea in 2009. He is currently researcher of Korea Aerospace Research Institute, Korea. Kyu-Hyun Han received a B.S. degree in Mechanical Design Engineering from Hanbat National University, Korea in 2002. He received master degree in Mechanical Design Engineering from Chungnam National University, Korea in 2004. He is currently researcher of Simuline Inc, Korea.     

The effect of a prosthetic crown’s design on the accuracy of mapping an abutment teeth’s shape

The objective is to carry out an in vitro assessment of tightness of Co–Cr–Mo alloy premolar and molar crowns manufactured with the use of the following technologies: casting, milling and laser melting. In order to compare the fit of crowns to abutments that served as the reference models, the Geomagic Qualify 12 software for structured-light 3D scanning and modelling was used. According to analyses of reports in the form of maps and summaries, all histograms and maps are characterized by low positive and negative values of shape deviations. All employed technologies were found to have a comparable, satisfactory accuracy of mapping the shape both in the area of the stair step and the area of side walls. The results of the studies enable to conclude that the tightness of prosthetic crowns manufactured with the use of the studied technologies is comparable and meets clinical criteria.     

Developing a bio-mechanotronic probing system for estimating soft tissue Young’s modulus in vivo

In many medical applications such as rehabilitation, clinical palpation, and manipulation of organs, it is important to characterize soft-tissue properties accurately. This paper presents a bio-mechatronic probing system that could be used for estimating soft tissue Young’s modulus in vivo. The system employs an electromagnetic spatial displacement sensor. The accuracy and reliability of the system were investigated. In addition, the effect of indentation rate on the variation of the values of the measured effective Young’s modulus was also studied. A series of elastomers with different Young’s modulus (ranged from 13.08 to 36.19 kPa) were assessed with both the probing system and a Hounsfield material testing machine. Intra-individual and inter-individual variations of the system were tested by five independent operators. The probing system was applied to assess the effective Young’s modulus of human body parts in vivo. Fifteen healthy female subjects with age of 22.5 ± 4.3 years old were included for the in vivo test. The system was shown to be highly accurate (R ² = 0.995) in comparison with the results obtained by the mechanical testing machine and had good reliability (intra-individual variation = 5.43%, inter-individual variation = 5.99%). The average effective Young’s modules of the region of umbilicus were 13.33 and 10.71 kPa for two different sites, respectively. Based on the results obtained, it is believed that this probing system was an accurate and reliable tool for rapidly assessing the mechanical properties of human body tissues in vivo.     

A study of a nano-sized water droplet’s transition from a flat surface to a pillared surface

The ability to control the hydrophobicity of a surface is of importance to many industries. The dynamic behavior of nano-sized water droplets moving from a flat surface to a pillared surface using molecular dynamics simulations was investigated. Simulations were carried out in two steps. In the first computational step, the initial group of water molecules reached equilibrium on a flat graphite surface. In the second computational step, a constant force was applied to the water droplet and the motion of the water droplet was evaluated as it moved from the flat surface to the pillar-type surface. The movement of the water droplet could be grouped into three different categories and depended on the pillar height and the magnitude of the applied force. The results showed the strongest body force with a pillar height of 6 graphite layers allowed most of the water molecules to move along the top of the pillars. In conclusion, a strong force and pillar height approximately half of the droplet height displayed the best transition from a flat surface to a pillared surface.

     

Finite element study for determination of material’s creep parameters from small punch test

Compared with the conventional tensile creep test, it is much more difficult to obtain the creep properties of a material by the small punch creep test due to the complex deformation response and stress distribution in the miniature specimen of the material. Although creep behavior has been investigated by the small punch test, most studies have been limited to a specimen geometry and therefore, cannot be extended to other conditions conveniently. In this study, a new developed analysis routine is presented to derive the creep parameters of a material using data obtained from the small punch creep test. With the aid of the finite element method, the displacement and the displacement rate of the small punch are obtained for different load levels. The relationship between the stress and creep strain of the specimen and the applied load and the punch displacement is obtained by a dimensional analysis and the membrane stretching model. The creep properties obtained from small punch tests and the conventional creep tests are also compared. The values of the creep properties between the two types of tests agree well with each other within an acceptable accuracy range. This indicates that it is possible to obtain the creep parameters of a material from the small punch creep test instead of the conventional creep test by the analysis routines proposed in this study. Some suggestions for data reduction of the small punch creep tests are also presented to obtain more accurate material creep parameters.     

Noise reduction of a high-speed printing system using optimized gears based on Taguchi’s method

To meet the increasing demand for more quiet printers, a noise reduction method is required for high-speed laser beam printing. The driving-gear noise is one of the most important components influencing the noise level in laser beam printers. In this paper, optimized gear designs based on Taguchi’s method are presented. The proposed optimized gears are applied to a high-speed laser beam printer. The design parameters for the plastic gear are selected during optimization as follows: a pressure angle of 20°, a helix angle of 20°, a module of 0.5, and a profile coefficient of 1.4/0.2/1.2 (cutter addendum × module / cutter tip radius × module / cutter dedendum × module). Through the Taguchi method, the prominence ratio and loudness in the sense of human hearing range, as well as the sound pressure level (SPL) are also reduced in the present printing system.     

Design and analysis of a new AUV’s sliding control system based on dynamic boundary layer

The new AUV driven by multi-vectored thrusters not only has unique kinematic characteristics during the actual cruise but also exists uncertain factors such as hydrodynamic coefficients perturbation and unknown interference of tail fluid,which bring difficult to the stability of the AUV’s control system.In order to solve the nonlinear term and unmodeled dynamics existing in the new AUV’s attitude control and the disturbances caused by the external marine environment,a second-order sliding mode controller with double-loop structure that considering the dynamic characteristics of the rudder actuators is designed,which improves the robustness of the system and avoids the control failure caused by the problem that the design theory of the sliding mode controller does not match with the actual application conditions.In order to avoid the loss of the sliding mode caused by the amplitude and rate constraints of the rudder actuator in the new AUV’s attitude control,the dynamic boundary layer method is used to adjust the sliding boundary layer thickness so as to obtain the best anti-chattering effects.Then the impacts of system parameters,rudder actuator’s constraints and boundary layer on the sliding mode controller are computed and analyzed to verify the effectiveness and robustness of the sliding mode controller based on dynamic boundary layer.The computational results show that the original divergent second-order sliding mode controller can still effectively implement the AUV’s attitude control through dynamically adjusting the sliding boundary layer thickness.The dynamic boundary layer method ensures the stability of the system and does not exceed the amplitude constraint of the rudder actuator,which provides a theoretical guidance and technical support for the control system design of the new AUV in real complex sea conditions.     

Contactless Online Method for Checking-Up a Net-Shaped Curtain’s Tension of a Radio-Reflecting Surface of Large Umbrella Reflector Antenna

A new contactless method for checking-up a net-shaped curtain’s tension of a radio-reflecting surface of a large umbrella reflector antenna is presented. The method is based on revealing the correlation between Moiré patterns and net-shaped curtain uniformity and tension. The advantages of the method are presented. Its main advantage lies in the fact that it is possible to set the netshaped curtain on the folding skeleton of an antenna reflector in the online mode. A way to apply the method is presented.     

Reconstruction of emission coefficients for a non-axisymmetric coupling arc based on MALDONADO’s method

The reconstruction of emission coefficient is a key factor for the calculation of temperature field.However,most of the researches for determining arc plasmas are based on axisymmetric sources,little has been done to study non-axisymmetric arc plasmas.In order to reveal temperatures of a non-axisymmetric coupling arc,the distribution of emission coefficients must be reconstructed in advance.In this paper,the argon atomic line intensities of the coupling arc are obtained by using the imaging system that involves a high speed camera in conjunction with a neutral and a narrow-band filter.The converted programme between emission coefficients and emitted intensities is programmed based on MALDONADO’s method.A displaced Gaussian model is used for evaluating the validity of the converted programme.Then,the emission coefficients of a free burning arc are reconstructed by MALDONADO’s method and an Abel inversion,respectively,and good agreement is obtained.Finally,the emission coefficient profiles of the coupling arc are achieved.The results show that the distribution of emission coefficient for the coupling arc is non-axisymmetric.The emission coefficient profile is similar to an ellipse,and the short axis of the ellipse is in the direction that the two electrodes are arranged along.The peak temperature of the coupling arc is in the middle of both electrodes.There is a strong interaction between both arcs within the coupling arc.The proposed research solves difficulties for determining asymmetric arcs and enlarges the application scope of spectroscopic techniques.     

Enhancement of JET’s mirror-link near-ultraviolet to near-infrared divertor spectroscopy system

Since 1994, JET has had a mirror-link spectroscopy system with a poloidal view of 150 mm of the outer divertor split into three ranges: near-ultraviolet (near-UV) (～ 300–450?nm), visible (450–750 nm), and near-infrared (near-IR) (750–1200 nm). The system consists of three Czerny–Turner/charge coupled device (CCD) pairs: 1 m focal length for the near-UV, 0.75 m focal length for the visible, and 0.5 m focal length for the near-IR. All were aligned along the same optical path to the divertor. As part of the JET ITER-like wall enhancements, the diagnostic system will be upgraded in five areas: (1) frame rate, (2) quantum efficiency (QE), (3) radial coverage, (4) optical throughput, and (5) for the near-UV, spectral resolution and survey capability. New CCDs for the near-UV and visible will have increased QE and allow three times frame rate. The near-UV will benefit from a 0.75 m imaging spectrometer with three gratings. The optics have been redesigned to allow ～ 360?mm view and greater than two times throughput. This paper will look at the design and implementation as well as the new diagnostic capabilities of the system.     

Evaluation of a digital data acquisition system and optimization of n-γ discrimination for a compact neutron spectrometer

A compact NE213 liquid scintillation neutron spectrometer with a new digital data acquisition (DAQ) system is now in operation at the Physikalisch-Technische Bundesanstalt (PTB). With the DAQ system, developed by ENEA Frascati, neutron spectrometry with high count rates in the order of 5×10(5) s(-1) is possible, roughly an order of magnitude higher than with an analog acquisition system. To validate the DAQ system, a new data analysis code was developed and tests were done using measurements with 14-MeV neutrons made at the PTB accelerator. Additional analysis was carried out to optimize the two-gate method used for neutron and gamma (n-γ) discrimination. The best results were obtained with gates of 35 ns and 80 ns. This indicates that the fast and medium decay time components of the NE213 light emission are the ones that are relevant for n-γ discrimination with the digital acquisition system. This differs from what is normally implemented in the analog pulse shape discrimination modules, namely, the fast and long decay emissions of the scintillating light.     

Further Development of Oxley’s Predictive Force Model for Orthogonal Cutting

An analytical modelling approach based on Oxley's predictive machining theory is presented to evaluate the cutting forces, chip thickness and temperature distributions in the orthogonal cutting process. In this approach, the work material properties are modelled using the Johnson–Cook constitutive material law, which represents the flow stress of the material as a function of strain, strain rate, and temperature. For the determination of the tool-chip interface temperature, an evenly distributed rectangular heat source near the cutting edge is used instead of a plane heat source. The tool thermal model is simplified by neglecting the temperature variations along the tool-chip interface to avoid the high cost of computation time. Finite difference method is applied for solution of the thermal model. The performance of the developed model is validated with the experimental data in machining of steel 1045. A comparison of the outputs from Oxley's original model and the modified model is provided. The model is further assessed by using two other materials, Al 6086-T6 and Ti6Al4V. Close agreements with experimental results have been shown.     

Value stream mapping and benefit–cost analysis application for value visibility of a pilot project on RFID investment integrated to a manual production control system—a case study

The importance of responding to customer demand to stay competitive in the global market and to increase market share has been increasing for companies lately. Due to demand fluctuations and difficulties to estimate it, gradually it becomes more difficult to sustain profitability and to fulfill demand. The company’s main problem is how to cut costs while producing small numbers of many types of products. For that reason, cost-conscious companies have focused on monitoring and controlling manufacturing and supplier-related activities by means of manual/electronic control devices in order to enhance the efficiency in the supply chain management and logistics process. This paper presents a case study about deployment of radio frequency identification (RFID) technology-based electronic Kanban system in an automotive industry supplier firm. In this project, by deploying RFID technology in a pilot area within the current manual Kanban system of this company, it has been possible to measure the true value added time in the production process. Value stream mapping is used to exhibit the mandatory requirements of RFID technology deployment in the shop floor. As a part of the study, we generate a current value stream map and a future value stream map, which contain the recommended revisions for the automotive supplier company. To evaluate the return of the investment, performance metrics were established and benefit–cost analysis is made. Obviously, future gains will include better inventory management to reduce the inventory levels within the production system.     

General bounds for the optimal value of retailers’ reorder point in a two-level inventory control system with and without information sharing

In this study, an inventory system consisting of a single product, one supplier, and multiple identical retailers is considered. Each retailer replenishes inventory from the supplier according to the well known (R,Q) policy. Transit times are constant and retailers face independent Poisson demand. The supplier utilizing the retailers' information in decision making for replenishment policy with a given order size starts with m initial batches (of size Q) and places an order in a batch of size Q to an outside source when a new order is placed. In this inventory system, excess demand is backordered, delayed orders are satisfied on a first-come first-serve basis, and no partial shipment is allowed. By partitioning the cost function of this system, general upper and lower bounds for the optimal value of R are determined. Based on several numerical examples, it is shown that these bounds (especially the lower bound) allow the optimal reorder point to be found more effectively with a shorter solving time.     

On the Allowance for Direct Piezoelectric Effect when Studying the Pulsed Operation Mode of a Piezoelectric Emitter by d’Alambert’s Method

An emitter in the form of a piezoelectric plate loaded on an aqueous medium is considered. Composite waveforms consisting of two half-periods are considered as electric signals fed to the plate, with one half-period exciting and the other one compensating. The pulsed transducer output signal is studied by D’Alambert’s method (without allowance for direct piezoelectric effect) and the Fourier spectral method. The similarity of the results indicates the correctness of applying d’Alambert’s method and the possibility for using it to assess the shape of signals emitted by the piezotransducer.     

Novel method for equivalent stiffness and Coulomb’s damping ratio analyses of leaf spring

The leaf spring is a representative type of laminated structure. Based on the linear theories of curve beams, the first derivatives of the leave??s status-vector of the leaf spring are provided. The first derivatives of the combination status-vector are obtained by properly dealing with the nonlinear interacted forces between adjacent leaves. Moreover, the precise integration technology and the transform matrix method are introduced to solve the equations. The force-displacement curve of a leaf spring is then calculated separately by using the present method and the finite element software ANSYS. From the results, the precision and advantages of the present methods for analyzing the leaf spring are revealed. The Coulomb??s damping ratio of the leaf spring is studied by using the present method.     

Numerical simulations of nano-particle’s drag forces using DSMC method for various Knudsen numbers

Journal of Mechanical Science and Technology - In this study, high-vacuum flow was analyzed using the direct simulation Monte Carlo (DSMC) method, and various forces acting on fine particles in a...     

A study on the variation of the performance and the cost of power generation in a combined heat and power plant with the change of the user facility’s return temperature

Journal of Mechanical Science and Technology - A combined heat and power (CHP) system generates electricity from thermal energy and generates heat by utilizing the remaining thermal energy. The...