Dimensions Of Legs Research Articles

Phylogenetic patterns of leg morphometric traits in vespid wasps (Hymenoptera: Vespidae)

AbstractVespid wasps use legs primarily for locomotion and in contexts such as grooming, handling of food and nest materials. Studies on leg form and function are relatively scarce. We analysed measurements of legs of 127 species of all genera of Polistinae, and of 18 species of other subfamilies, with the intent of investigating the occurrence and phylogenetic locations of morphometric patterns. Body‐size variation across Polistinae was determinant as to the absolute dimensions of legs, but allometric effects are generally small when comparing proportional length differences between differently sized species. Quite differently, size‐independent shape aspects are notably distinct as expressed by regression residuals and are clearly phylogenetically structured. Most distinctive are the very long mid and hind legs (and simultaneously exceedingly short forelegs) of Mischocyttarus species, and the comparatively shorter legs of some Epiponini. We found that forelegs have evolved with relative independence of the mid and hind legs, which is probably related to functions associated with the transport and manipulation of food and materials. Most examined solitary species showed mid and hindlegs shorter than most social polistines and vespines. Forefemur shape in some solitary species (euparagiines, masarines and some eumenines) may be functionally related to fossorial habits.

Method of reinforcing defects in field welds of unique buildings and structures

Introduction. The article presents a new method of reinforcing field welds with defects, impermissible according to the regulation requirements. This method allows reinforcement works to be carried out while maintaining the functional purpose of a building or structure without closing for the repair.Aim. To develop a technology of reinforcing defective welds, which preserves the functional purpose of a structure during repair works without its closure.Materials and methods. Reinforcement is carried out using a sheet of high-strength steel. The reinforcing sheet must be attached to connected field elements, which excludes the defective weld from the operation. Welders are permitted to perform works after testing on control welded joints. Welds, made by a candidate welder, is cut and sent to a specialized laboratory for determining weld strength properties, impact strength of weld macro- and microstructures, as well as the order and dimensions of legs for multi-pass welds. If the obtained weld data meets the standard indicators, the candidate welder is permitted to connect the reinforcement sheets of defective field welds. After making welded joints, they must be checked by visual, instrumental and ultrasonic testing.Results. A method of reinforcing defective welds was developed and implemented. Defects in the welds appeared during the connection of field elements, whose dimensions were less than the transport size, into a single spatial system, for example, the inner contour of a dome cover. This type of reinforcement can be made without closing the building or structure for repair works.Conclusion. The method of weld reinforcement can be used to remedy impermissible derects, detected by visual, instrumental and ultrasonic testing, in any buildings and structures, including unique long-span ones, therefore ensuring their reliable and safe operation after the construction.

A comprehensive analytical model for thermoelectric body heat harvesting incorporating the impact of human metabolism and physical activity

Wearable electronic devices, which can provide hassle-free, long-term, continuous monitoring for different health parameters are of interest for a variety of applications including managing chronic diseases and post-operative patient care. Thermoelectric generators (TEGs) that rely on the Seebeck effect provide a promising path to self-powered wearable electronics via harvesting body heat. The net harvested energy depends on several factors including metabolic heat, core body temperature, and skin resistance, which are regulated by the human thermoregulatory system. These factors are influenced by age, sex, height and body mass index (BMI) and they can cause appreciable differences in the amount of harvested energy. In this paper, we present a comprehensive model, which combines an analytical TEG model with established biological models for the human body to accurately predict the performance of a wearable TEG. The model calculates variations in metabolic rate and core body temperature during physical activity, which are then used to calculate the skin resistance and the skin temperature following an iterative procedure. These parameters are then used to determine the temperature differential across the TEG and the resulting output power delivered to an external load. Experimental validation of the model was achieved using a wrist worn flexible TEG during different physical activities, which were carefully designed to separate the impact of convection from the human thermoregulatory response. It was determined that increase in metabolism from normal walking could lead to a 20% increase in the TEG output voltage. The model was used to predict the impact of age and sex on TEG output power. The results indicate that age can have a significant impact on TEG performance. It is shown that the power generated by adults over the age of 65 can be 30%–35% less than the power generated by younger adults under the age of 30. This reduction in power was attributed to an increase in skin resistance, which was found to be 13% for females and 25% for males. The skin resistance of females was also found to be higher, which correlated well with their higher average fat content. The overall impact of sex was found to be smaller than age, females generating 5%–10% less power than males. The model takes into account all pertinent TEG parameters including properties of the semiconductor materials, physical dimensions of the semiconductor legs, fill factor and electrical and thermal parasitic resistances. Using these input parameters, and modeling of the human body as a heat source, the model can help optimize TEG module design for a specific wearable application.

Comprehensive performance prediction and power promotion for wearable thermoelectric generator with flexible encapsulation in practical application

With ability of converting the heat harvested from human body into electricity, the wearable thermoelectric generators (WTEGs) are attracting lots of interests for self-powered electronic devices. However, the output power density of the WTEG is limited for supplying the electronic devices. Therefore, the performance enhancement by optimal design of the developed WTEGs is needed. In this paper, a method of comprehensive modeling of a WTEG is proposed by considering all essential components and realistic boundary conditions. By solving the model with finite element modeling (FEM) method, the calculation performances agree well with experimental results at various temperature difference and load resistance. Through the temperature and voltage distribution of the WTEG obtained, the effects of side heat loss and heat conduction of the encapsulation are revealed. Besides, the impact of the thermal conductivity of encapsulation and the geometric dimensions of thermoelectric legs on the output performance are explored. Finally, the performance prediction results indicate that at the temperature difference of 15 K, the output power of the WTEG with optimized design can be improved about 598.1% with matched loading resistance compared to the device with original design.

Design of Jack-Up Platform for 6 MW Wind Turbine: Parametric Analysis Based Dimensioning of Platform Legs

Abstract The article presents the results of the research conducted within the framework of the project entitled WIND-TU-PLA (ERA-NET, MARTEC II), the general aim of which was to design and analyse supporting structures for wind turbines intended for operation on the South Baltic area. The research part described in the article aimed at developing a preliminary design for a jack-up platform which can operate on water areas with depth of 40 m. The main task was to determine optimal dimensions of platform legs and the radius of their spacing. Two jack-up platform concepts differing by spacing radius and hull dimensions were designed with the intention to be used as a supporting structure for a 6-MW offshore wind turbine. For each concept, the parametric analysis was performed to determine optimal dimensions of platform legs (diameter Dleg and plating thickness tleg). Relevant calculations were performed to assess the movements of the platform with parameters given in Table 1 in conditions simulating the action of the most violent storm in recent 50 years. The obtained results, having the form of amplitudes of selected physical quantities, are shown in comprehensive charts in Fig. 6 and 7. Based on the critical stress values (corresponding to the yield stress), the area was defined in which the impact strength conditions are satisfied (Fig. 14). Then, the fatigue strength analysis was performed for two selected critical leg nodes (Fig. 12). Its results were used for defining the acceptable area with respect to structure’s fatigue (Fig. 14). Geometric parameters were determined which meet the adopted criteria, Table 6. The decisive criterion turned out to be the fatigue strength criterion, while the yield point criterion appeared to be an inactive constraint.

Numerical simulation of thermoelectric performance of linear-shaped thermoelectric generators under transient heat supply

A two-dimensional, dynamic finite element model is developed to study the transient characteristics of linear-shaped thermoelectric generators (L-TEG) in this paper. The model considers the effect of an unsteady heat source, which is regarded as a time-varying thermal boundary condition. The temperature-dependent TE material properties are also taken into account. For two loading processes (i.e. heating process and cooling process), we investigate transient TE behaviors of L-TEG under different loading ways and duration of thermal load as well as geometric dimensions of the TE legs, individually. The results indicate that, in heating process, the responses of the power and the absorbed heat to the thermal load present obvious time delay under some certain conditions; in the cooling process, interestingly, an internal heat source emerges in the L-TEG, caused by the delay of thermal diffusion from the hot end of the TE legs to cold end. This heat source renders a heat release from the generator to the ambient. A process relying on its own heat to generate electricity is thus formed. This study further helps the understanding of TE behavior of TE generators in service.

Solving elastic deformation of some parallel manipulators with linear active legs using computer-aided design variation geometry

It has been a significant and challenging issue to determine the elastic deformation of parallel manipulators for their precision analysis and control. A new method is proposed and studied for solving the elastic deformation of some parallel manipulators with linear active legs using computer-aided design variation geometry. First, an original simulation mechanism of a parallel manipulator is constructed; each of the vectors in the force transformation matrix of the parallel manipulators is constructed by this simulation mechanism. The active/constrained wrench and their pose are determined based on the Newton–Euler formulation. Second, the elastic deformed dimensions of the active legs are determined based on the elastic deformation equation and the active/constrained wrench. Third, a new simulation mechanism of this parallel manipulator is constructed by replacing the original dimensions of active legs with the deformed dimensions of active legs and the elastic deformations of parallel manipulators are solved using the pose difference between the original and new simulation mechanisms. Finally, two parallel manipulators are illustrated and their elastic deformations are solved and verified by both analytic approach and finite element method.

A Resistance Ratio Analysis for CoSb3-Based Thermoelectric Unicouples

In the search for desirable materials for use in thermoelectric generators, CoSb3-based skutterudites have stimulated much scientific interest due to their high performance capabilities even at high temperatures. In this work, we tested the electrical power-generation characteristics of CoSb3-based unicouples. We manufactured power-generation unicouples using n-type In0.25Co3.95Ni0.05Sb12 and p-type In0.25Co3.0Fe1.0Sb12 legs. The dimensions of the thermoelectric legs were 10 mm in diameter and 10 mm in height, with Cu sheets and Cu/Mo alloy as the electrode materials. For our unicouples, we evaluated the resistance ratio m′ (=Ro/R), which represents the ratio of the load resistance to the internal resistance of the unicouple. From this analysis of the resistance ratio m′, we obtained a considerable amount of information about the loss factors that caused the difference between the measured power output and the theoretical value. Through these analyses of two types of loss factors, we sought to improve the open-circuit voltage and internal resistance of a unicouple with CoSb3/Ti/electrode interfaces. In addition, a long-term durability test of the unicouple at high temperature was performed to test the stability of the thermoelectric materials and of the interface between the electrodes and the thermoelectric legs at the same time.

Application of computed tomography for the evaluation of obstetrically relevant measurements in German Holstein-Friesian calves

The aim of this study was to measure obstetrically relevant dimensions in calves manually and via computed tomography and to investigate their relationship with the dimensions of fetal body parts that are accessible to the obstetrician during early stages of vaginal delivery. Twenty Holstein-Friesian stillborn calves (Bos taurus) weighing 41.1 ± 3.7 kg (33.6–46.5 kg) were examined and the maximum height (H), width (W), circumference (C) and cross-sectional area (A) of their body was determined. The largest (P < 0.05) one-dimensional variable was the height of the thorax in the region of cranial sternum (H-Thorax; 29.3 ± 1.3 cm), and the largest (P < 0.05) two-dimensional variables were the cross-sectional area of the shoulder region at greater tubercles of the humeri (A-Shoulder; 307 ± 27 cm2) and of the thorax in the region of cranial sternum (A-Thorax; 306 ± 25 cm2). The dimensions of the front legs, which included the circumference of the canon bone and width of the fetlock joint, did not correlate (P > 0.05) with H-Thorax, A-Shoulder and A-Thorax. There were moderate significant correlations between the perpendicular height of the head (H-Head) and A-Thorax (r = 0.65, P < 0.05) and between the circumference of the head (C-Head) and A-Shoulder (r = 0.64, P < 0.05) and A-Thorax (r = 0.52, P < 0.05), but other relationships (P > 0.05) between the dimensions at the level of the head and H-Thorax, A-Shoulder and A-Thorax were not significant (P > 0.05). The results of this study show that the shoulders and thorax are the obstetrically most relevant calf dimensions, but the size of these variables cannot be reliably predicted by evaluating the dimensions of the forelimbs and head of calves during delivery.

Solving reachable workspace of some parallel manipulators by computer-aided design variation geometry

To shape the workspace of some novel parallel manipulators (PMs) is significant. A novel computer-aided design (CAD) variation geometry approach is proposed to shape and solve the reachable workspace of some PMs with three to six degrees of freedom (DOFs). Some basic techniques are described for designing the simulation mechanism and solving the reachable workspace. The simulation mechanisms of some PMs with three to six DOFs are created. When varying the driving dimensions of the active legs in the given extent, the simulation mechanisms vary correspondingly, and the position components of the moving platform are solved automatically. By transferring the position solutions into spatial spline curves in the simulation mechanism, all the boundary surfaces of the workspace can be created and visualized dynamically. Comparing with analytic approaches for solving workspace, the CAD variation geometry approach is simple, straightforward, accurate, and repeatable.

Power Generation of a p‐Type Ca3Co4O9/n‐Type CaMnO3 Module

Thermoelectric modules composed of eight pairs of p‐type Ca2.7Bi0.3Co4O9 (Co‐349) and n‐type CaMn0.98Mo0.02O3 (Mn‐113) bulks were constructed using Ag electrodes and paste including powder of the n‐type oxide. The former bulks were prepared by hot pressing. On the other hand, the latter were densified using a cold isostatic pressing technique and sintered in atmospheric pressure. Dimensions of both oxide legs were 5 mm wide and thick and 4.5 mm high. An alumina plate was used as a substrate, and there was no alumina plate on the other side of the modules. When the substrate side was heated, the module could generate up to 1.0 V and 0.17 W of open circuit voltage (VO) and maximum power (Pmax), respectively, at a hot‐side temperature of 1273 K (furnace temperature as a heat source) and a cold‐side temperature of 298 K (circulated water temperature) in air. But internal resistance RI reached a value of 1.5 Ω, which is about six times higher than the calculated one from resistivity of both p‐ and n‐type bulks. When the substrate side was cooled, VO and Pmax reached 0.7 V and 0.34 W of VO and Pmax, respectively, at a furnace temperature of 1273 K.

Geometric optimization of thermoelectric coolers in a confined volume using genetic algorithms

The demand for thermoelectric coolers (TEC) has grown significantly because of the need for a steady, low-temperature operating environment for various electronic devices such as laser diodes, semiconductor equipment, infrared detectors and others. The cooling capacity and its coefficient of performance (COP) are both extremely important in considering applications. Optimizing the dimensions of the TEC legs provides the advantage of increasing the cooling capacity, while simultaneously considering its minimum COP. This study proposed a method of optimizing the dimensions of the TEC legs using genetic algorithms (GAs), to maximize the cooling capacity. A confined volume in which the TEC can be placed and the technological limitation in manufacturing a TEC leg were considered, and three parameters––leg length, leg area and the number of legs––were taken as the variables to be optimized. The constraints of minimum COP and maximum cost of the material were set, and a genetic search was performed to determine the optimal dimensions of the TEC legs. This work reveals that optimizing the dimensions of the TEC can increase its cooling capacity. The results also show that GAs can determine the optimal dimensions according to various input currents and various cold-side operating temperatures.

多脚構造物の簡易解析法に関する一考察 海洋構造物の横振動に関する研究（第３報）

In order to make a simple analysis for the lateral vibration of an off-shore structure constructed with multilegs and a platform, more simplified method than the one used in the 1st or 2nd report was applied to the structure by replacing it with the new analytical model, evaluating its flexural rigidity and then by transforming the structure into the equivalent lumped mass method. The new model proposed in this study was the vertical cantilever beam, the lower end of which was fixed, and the upper end of which was loaded by the axial load and constrained not to rotate, even if it could be displaced horizontally by the small amount of displacement.Furthermore, the validity of this model was examined by the model experiments carried out on three kinds of multi-leg-structures which had 8, 10 and 12 legs.The main results obtained are as follows:(1) The values of natural frequency and displacement for each structure vibrating in water are independent of the direction of vibration within the ranges of the leg-intervals and the dimensions of legs used in this study.(2) The natural frequency obtained by the proposed method, which utilizes the Theory (II) or Theory (IV) defined in this paper, coincides very well with the experimental frequency within the error range that is about 0.00-1.36%. The value of this range is a little lower than the value (0.07-3.57%) estimated by the Theory (2) or Theory (4) defined in the 2nd report, and so the proposed method in this study gives a little more precise natural frequency than the other methods.(3) Furthermore, the method in this study gives the fairly well estimation with respect to the amplitude of the lateral vibration of the multi-leg-structures, since the error involved in the estimation is only about 9-14% until the fifth period of vibration.(4) The value of the frequency or displacement estimated by the Theory (II) gives the same degree of the error range as one by the Theory (IV).(5) Finally, it can be realized that the simple method proposed in this paper could be satisfactorily available for analyzing the lateral vibration of the practical off-shore structure with multi-legs.