Free vibration analysis of a Timoshenko beam carrying multiple spring-mass systems with the effects of shear deformation and rotary inertia

Der-Wei Chen,Jee-Ray Wang,Tsung-Lung Liu 국제구조공학회 2007 Structural Engineering and Mechanics, An Int'l Jou Vol.26 No.1

Because of complexity, the literature regarding the free vibration analysis of a Timoshenko beam carrying “multiple” spring-mass systems is rare, particular that regarding the “exact” solutions. As to the “exact” solutions by further considering the joint terms of shear deformation and rotary inertia in the differential equation of motion of a Timoshenko beam carrying multiple concentrated attachments, the information concerned is not found yet. This is the reason why this paper aims at studying the natural frequencies and mode shapes of a uniform Timoshenko beam carrying multiple intermediate spring-mass systems using an exact as well as a numerical assembly method. Since the shear deformation and rotary inertia terms are dependent on the slenderness ratio of the beam, the shear coefficient of the cross-section, the total number of attachments and the support conditions of the beam, the individual and/or combined effects of these factors on the result are investigated in details. Numerical results reveal that the effect of the shear deformation and rotary inertia joint terms on the lowest five natural frequencies of the combined vibrating system is somehow complicated.

Free and forced vibrations of a tapered cantilever beam carrying multiple point masses

Chen, Der-Wei,Liu, Tsung-Lung Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.23 No.2

The exact solutions for the natural frequencies and mode shapes of non-uniform beams carrying multiple various concentrated elements

Chen, Der-Wei Techno-Press 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.16 No.2

From the equation of motion of a "bare" non-uniform beam (without any concentrated elements), an eigenfunction in term of four unknown integration constants can be obtained. When the last eigenfunction is substituted into the three compatible equations, one force-equilibrium equation, one governing equation for each attaching point of the concentrated element, and the boundary equations for the two ends of the beam, a matrix equation of the form [B]{C} = {0} is obtained. The solution of |B| = 0 (where ${\mid}{\cdot}{\mid}$ denotes a determinant) will give the "exact" natural frequencies of the "constrained" beam (carrying any number of point masses or/and concentrated springs) and the substitution of each corresponding values of {C} into the associated eigenfunction for each attaching point will determine the corresponding mode shapes. Since the order of [B] is 4n + 4, where n is the total number of point masses and concentrated springs, the "explicit" mathematical expression for the existing approach becomes lengthily intractable if n > 2. The "numerical assembly method"(NAM) introduced in this paper aims at improving the last drawback of the existing approach. The "exact"solutions in this paper refer to the numerical results obtained from the "continuum" models for the classical analytical approaches rather than from the "discretized" ones for the conventional finite element methods.

On the eigenvalues of a uniform rectangular plate carrying any number of spring-damper-mass systems

Chen, Der-Wei Techno-Press 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.16 No.3

The goal of this paper is to determine the eigenvalues of a uniform rectangular plate carrying any number of spring-damper-mass systems using an analytical-and-numerical-combined method (ANCM). To this end, a technique was presented to replace each "spring-damper-mass" system by a massless equivalent "spring-damper" system with the specified effective spring constant and effective damping coefficient. Then, the mode superposition approach was used to transform the partial differential equation of motion into the matrix equation, and the eigenvalues of the complete system were determined from the associated characteristic equation. To verify the reliability of the presented theory, all numerical results obtained from the ANCM were compared with those obtained from the conventional finite element method (FEM) and good agreement was achieved. Since the order of the property matrices for the equation of motion obtained from the ANCM is much lower than that obtained from the FEM, the CPU time required by the ANCM is much less than that by the FEM.

Seasonal yeast compositions in Forcipomyia taiwana (Diptera: Ceratopogonidae)

Hung-Wei Chen,Jui-Yu Chou,Chung-Chi Lin,Yu-Der Wen,Wei-Lung Wang 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.2

Forcipomyia taiwana, a biting midge, is one of the most annoying blood-sucking pests in Taiwan. The larvae of Forcipomyia species feed primarily on algae, and the adults feed on nectar for nutrition. After mating with male adults, females bite humans and digest blood for the formation and development of their eggs. The bites often cause human itching, swelling, skin lesion and even fatal shock. Harassment from this biting pest has become a serious problem and has influenced the quality of outdoor recreational activities. Thus, it is necessary to understand the ecology of F. taiwana to develop an effective control strategy. This study showed the seasonal variation of yeast compositions in the interior of F. taiwana. Furthermore, we found that Aureobasidium spp. appeared the most during collection times and these yeasts are able to decompose the cellulose, a major component in the cell wall of algae and Oomycete fungi. These fungi infect a broad range of host and have adverse effect on fitness of the biting midges. Thus, Aureobasidium spp. play a crucial role in the defense system of F. taiwana against pathogens. The study provides useful information that could be used in the development of biocontrol strategy in the future.

DETECTION OF SOFT-TISSUE CALCIFICATION IN UREMIC PATIENTS BY Tc-99m MDP BONE SCINTIGRAPHY

Chen, Wei Lian,Shieh, Shang Der,Huang, Han Wen 대한핵의학회 1984 핵의학 분자영상 Vol.18 No.1

Effects of Dietary Heat Extruded Soybean Meal and Protected Fat Supplement on the Production, Blood and Ruminal Characteristics of Holstein Cows

Chen, Kuen-Jaw,Jan, Der-Fang,Chiou, Peter Wen-Shyg,Yang, Der-Wei Asian Australasian Association of Animal Productio 2002 Animal Bioscience Vol.15 No.6

The purpose of this study was to evaluate the effect of protected fat and heat-extruded soybean meal on the lactation performance of Holstein cows. Twenty-four cows, consisting of 20 lactating cows and 4 rumen-fistulated dry cows, were randomly allocated into four groups with 5 lactating cows and 1 fistulated cow in each group. A replicated 4${\times}$4 Latin square design with four 21 day periods, including 14 days of adaptation and 7 collection days within each period was employed. The experiment was a 2${\times}$2 arrangement, with or without heat-extruded soybean meal and protected fat inclusion. The dietary treatments consisted of supplements of (a) soybean meal (the control), (b) heat-extruded soybean meal, (c) protected fat, and (d) heat-extruded soybean meal and protected fat. The results showed that there were no significant differences in feed intake, milk yield, milk protein content, milk lactose content and body weight change between the dietary treatments. However, cows supplemented with protected fat showed a significantly increased (p<0.05) milk fat yield, 3.5% FCM and total solid yield. The increase in undegradable intake protein (UIP) via heat extruded soybean meal supplement significantly decreased the urea nitrogen concentration in the blood (p<0.05). Dietary fat inclusion significantly increased the blood cholesterol concentration (p<0.01) and decreased the ruminal pH value (p<0.01). Increased dietary UIP significantly decreased the ammonia nitrogen concentration in the rumen (p<0.01), but did not significantly influence the pH and VFA molar percentage in the rumen. It appears that dietary protected fat inclusion could improve milk fat and solid content. Increased dietary undegradable intake protein through heat extruded soybean meal did not improve milk yield. But it could alleviate the adverse effect of decreased milk protein due to dietary fat supplementation. Increased UIP could also decrease the ammonia nitrogen concentration in the rumen and plasma urea nitrogen concentration in the blood.

A review of research on teacher efficacy beliefs in the learner-centred pedagogy context: Themes, trends and issues

Wei Ching Lee,Victor Der-Thanq Chen,Li-Yi Wang 서울대학교 교육연구소 2017 Asia Pacific Education Review Vol.18 No.4

Accompanying the trend of schools moving from teacher-centred to learner-centred pedagogy (LCP) practices, researchers have argued that teachers switching from the one to the other may as a result make changes in their personal judgement of their own teaching competency. This review aims to provide a comprehensive overview of recent studies of teacher efficacy beliefs (TEB) in relation to the LCP context. We have adopted a grounded approach to review 34 published papers between January 2009 and April 2016. Six themes were identified from our analysis of the findings of these studies to delineate how TEB has been studied in the LCP context. By a comparison with other two influential reviews on TEB research, we have also identified three trends and five issues in TEB research in LCP context. Future research directions are proposed with the intent to engage researchers sharing the same interest in this field.

Processing of high conductive Bi2O3/8YSZ composites as SOFC electrolyte

Li-Der Liu,Yu-Hung Cheng,Wen-Chen J. Wei 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.4

Dual-phasic composites consisted of continuous Bi2O3 matrix and 8 mol% yttria stabilized zirconia particulates were prepared by solid-state-sintering or liquid-phase-sintering, and investigated over the temperature range between 250-650 oC to reveal good electrical conductivity and matched thermal expansion to the components used for intermediate-temperature solid oxide fuel cell (SOFC). Interface reactions occurred during sintering either at 750 oC or 900 oC could enhance the diffusion of Zr, Y and Bi ions, to form effective diffusion zone for stabilizing δ-Bi2O3 matrix. The results showed a dual-structure of 66 mol% 8YSZ-34 m% Bi2O3 with up to 76% δ-phase content was stabilized by solid-state sintering, surpassing a bulk conductivity of 10−2 Scm−1 at 500 oC. The coefficient of thermal expansion value exhibited by the composite between 25 oC and 650 oC was found to be 10-12.2 ppm*K−1, which was in good agreement with that of CeO2-based electrolyte. Thus, it was confirmed that the addition of ZrO2 could stabilize the Bi2O3, by improving its capability as a solid electrolyte for intermediate temperature SOFC

Force Controlled Robot Gripper with Flexible Joint for Delicate Assembly Task

Chwan-Hsen Chen,Wei-der Chong 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

For automatic assembly tasks in electronics manufacturing industries, grasping force control for the gripper is required when handling delicate electronic parts, because excessive force could permanently deform or even damage the parts. Furthermore, in order to grasp odd-shaped components, the ‘fingers’ of the gripper should be adaptive to the work-piece’s shape in order to maximize the contact area. To meet these requirements, we propose a five-bar linkage gripper design with a compliant finger joint. This under-actuated linkage design can grasp irregular shaped work-piece and maintain the direction of the applied force along the gripper closing direction. The compliant joint design adopts an innovative clamped-and-pivoted flexible beam configuration, with one end of the beam fixed to the finger’s tip and the other end rotating with a joint. The angular displacement of the beam, which is a linear function of the grasping force, is measured by a magnetic rotary encoder. Therefore, the grasping force can be controlled by monitoring the angular deflection of the beam. An additional advantage of the compliant linkage design is the gripper can adapt to the centerline misalignment between the gripper and the mating part along the gripper closing direction during an insertion task due to the joint compliance. Based on the mentioned concept, a two-fingered under-actuated gripper is developed. Grasping experiments on objects with different stiffness and shapes, like electromagnetic shield for mobile phone PCB, are conducted to verify the gripper’s performance on force control and shape-adaptability. All goals are achieved with satisfactory results.