Aluminum Bar Research Articles

18 Comparison of Topical Agents for Eschar Removal in Porcine Model: Bromelain-enriched vs. Traditional Collagenase Agents

IntroductionSurgical excision and grafting of deep partial thickness (DPT) and full thickness (FT) burns is a cornerstone of modern burn wound care. Use of commercially available topical enzymatic agents has been limited due to slower and less complete eschar removal than surgical excision. Using a porcine model of DPT and FT burns, we compared the eschar removal efficacy of a bromelain-enriched enzymatic agent derived from the stems of pineapple plants and a commercially available collagenase.MethodsUnder an approved animal welfare committee protocol, we created 10 DPT and 10 FT burns measuring 2.5 by 2.5 cm on each of four anesthetized Yorkshire pigs weighing 30 kg using a preheated aluminum bar applied to the dorsum and flanks of the animals. For DPT burns, the bar was preheated to 80ºC and applied for 20 seconds with a pressure of 2 kg. For FT burns, the bar was preheated to 100ºC and applied for 30 seconds. Eschar removal was initiated 24-hours later. Two pigs each were randomly assigned to collagenase or the bromelain-enriched agent. The bromelain-enriched agent was applied topically once on day 1 for a period of 4 hours followed by a 2-hour soaking period with normal saline. The collagenase was applied topically daily as per manufacturer instructions until complete removal of the eschar or for up to 14 days. The primary outcome was the percentage of burns with complete eschar removal assessed by a masked observer at 1, 10 and 14 days after application.ResultsA total of 40 FT and 40 DPT burns were created on the four pigs. Regarding FT burns, all bromelain treated burns experienced complete removal of eschar on day 1 after the single 4-hour application. In contrast, none of the collagenase treated FT burns experienced complete removal of eschar after 14 days of treatment. At 10 days, 30% of collagenase treated burns had < 50% removed eschar; by day 14, 40% had >50% removed eschar and 15% had < 50% eschar removed. Regarding DPT burns, all bromelain treated burns had complete eschar removal after the single 4 hour application. In contrast, none of the collagenase treated burns experienced complete removal of eschar after 10 days; by day 14, 35% had complete eschar removal. At day 10, 10% of collagenase treated burns had >50% eschar removed and 75% had < 50% eschar removed; by day 14, 30% had > 50% eschar removed and 35% had < 50% eschar removed. There were no wound infections or any other adverse events noted.ConclusionsTopical treatment of DPT and FT porcine burns with a single 4-hour application of a bromelain-enriched enzyme resulted in complete eschar removal of all burns. In contrast, after 14 daily topical applications of the collagenase, none of the FT burns experienced complete removal of the eschar and in 35% of the DPT burns, eschar removal was complete.

ANALISIS PERANCANGAN TUNGKU PENGECORAN LOGAM ALUMUNIUM BERBAHAN BAHAN BAKAR OLI BEKAS GUNA MENEKAN BIAYA PRODUKSI DALAM PROSES PRODUKSI ALUMUNIUM BATANGAN

CV Mandiri Jaya Logam is a home industry which is engaged in metal casting which producesaluminum bars. The use of wood raw materials that is less effective and efficient for burningbased on the use of wood is very large for the production process, the costs used to purchasefuel are relatively expensive, the combustion system that produces high pollution. This type offurnace (crusible) using koi as a liquid aluminum container only has a resistance of 3 monthsand must be replaced. The refractory made of bricks prepared by the koi has cracks so it needsmaintenance every week, as a result of the heat and air pressure of the gasbull not being ableto be properly dampened by the bricks. natural gas and analyze the calculation of the cost ofproduction. The results of the stove design analysis of used fuel oil, wood, natural gas foundthat the stove design with natural gas fuel has good capability and durability, so that whenthe cost of production of natural gas fuel is analyzed, it has an economical cost for themanufacture of aluminum bar products at a price of Rp. 16,947 / kg

Tensor fascia latae and gluteal muscles myoelectric responses to increasing levels of hip medial rotation torque

Medial hip rotation is typically attributed to the tensor fascia latae (TFL) and lateral rotation, to the gluteus maximus. However, experimental studies in cadavers suggest that the TFL lacks a moment arm for medial rotation and that the gluteus maximus may act as hip medial rotator depending on the hip flexion angle. In order to address this contradictory thinking, we measured the myoelectric activity of TFL, gluteus medius and gluteus maximus (superior portion, GMaxS, and inferior portion, GMaxI) for increasing levels of medial rotation torque applied to the hip. To keep frontal and sagittal plane hip joint net torques constant during the experiments, the medial hip rotation torque was changed by displacing standard weights along an aluminum bar device, thereby producing pure medial hip rotation torques. The effect of increasing medial hip rotation torque was investigated for a fully extended hip (0°), and at 45° and 90° of flexion. We found an increase in the myoelectric activity of the TFL (∼90%↑, p = 0.002) at 90° of flexion and of the GMaxS (∼7%↑, p = 0.048) at the extended position with an increase in medial hip torque application (from 0 to 7.4 N.m.). For the GMed (regardless of hip position) and for the 45° position (regardless of muscle), no systematic changes across torque conditions were observed. In contrast to the common clinical assumption and current practice thinking, our results indicate that an increase in TFL activity is required to control for an increase in external torque towards hip medial rotation.

Deformation evolution and diffusion characteristics of polymethyl methacrylate under impact loading

Dynamic compression experiments on cubic polymethyl methacrylate (PMMA) specimens and two kinds of trapezoid PMMA specimens are carried by changing the transmission bars into steel bar and aluminum bar on the experimental device of split Hopkinson pressure bar (SHPB). The compression processes of PMMA specimens are recorded by high-speed photography, and the breakage processes of PMMA specimens are analyzed based on the force displacement curves and high-speed images. The evolutions of deformation and diffusion resistances of PMMA specimens under impact loading are discussed. The results show that the failure of the sample is caused mainly by the partial failure front at the contact end, and then the failure front propagates to the inside of the sample, leading the sample to break. The failure front of cubic sample is generated preferentially at the transmission end under low speed impact and at the incident end under the higher speed impact. After changing the shape of the specimen and the material of the transmission bar, the relaxation phenomenon is prominent, and the failure front occurs only at the incident end. The compressive deformation of the trapezoid sample before breakage is non-uniform, and the stress and strain in the sample gradually decrease with the increase of the cross section, and show a linear diffusion distribution. The strain distribution and shear activation diffusion equation are used to obtain the generalized diffusion resistance distribution of the failure front. The generalized diffusion resistance increases first in front of the failure front and decreases after the failure front, and the amplitude of the generalized diffusion resistance is related to the release of local strain energy.

Study on deformation evolution and diffusion characteristics of PMMA under impact loading

Dynamic compression experiments were carried out on cubic PMMA specimens and two kinds of trapezoid PMMA specimens by changing the transmission bars to steel and aluminum bar with the Loading device of split Hopkinson pressure bar (SHPB). The compression process of PMMA specimens was recorded by high-speed photography, and the breakage process of PMMA specimens was analyzed based on the force displacement curves and high-speed images. The evolution of deformation and diffusion resistance of PMMA specimens under impact loading was discussed. The results show that the failure of the sample is mainly caused by the partial failure front at the contact end, and then the failure front propagates to the inside of the sample and leads to the breakage of the sample. The failure front of cubic samples is preferentially generated at the transmission end under low speed impact and generated at the incident end under the higher speed impact. After changing the shape of the specimen and material of the transmission bar, the relaxation phenomenon is obvious, and the failure front only occurs at the incident end. The compressive deformation of the trapezoid sample before breakage is non-uniform, and the stress and strain in the sample gradually decrease with the increase of the cross section, and show a linear diffusion distribution. The strain distribution and shear activation diffusion equation were used to obtain the generalized diffusion resistance distribution of the failure front. The generalized diffusion resistance increases first in front of the failure front and decreases after the failure front and the amplitude of the generalized diffusion resistance is related to the release of local strain energy.

Influence of stress state on dynamic breakage of quartz glass spheres subjected to lower velocity impacting

The breakage process of glass spheres under impact loading is very complex due to the transition of two failure mechanisms, i.e. tensile failure and shear failure, with the increase of loading rate. In order to investigate the influences of stress state adjustment on sphere breakage, three kinds of transmission bars, i.e. steel bar, aluminum bar, PMMA bar, and double-sphere specimens are employed by the modified conventional Split Hopkinson Pressure Bar (SHPB) device. These experiments are conducted under lower impact velocity, which evaluated by the critical state of single sphere failure. Larger critical strain and lower critical strain rate for sphere breakage are obtained when replacing the steel transmission bar with the PMMA bar. The failure properties of inner geometric structures by adjusting failure sequences of the double-sphere specimens. Based on the evolution of particle size distributions and local deformation distribution by the Digital Image Correlation (DIC) method, two-stage failure model is obtained. The first stage of sphere breakage results from the diffusion of local Hertz cracks at the contact areas, which mainly caused by local shear failures, and the second stage results mainly from the penetrated oblique cracks along impact direction, which mainly caused by transversal tensile failures. Adjustment of stress and strain fields by these two schemes reveals these intrinsic influences on sphere breakage, and failure law, involving the effects of local strain, local strain gradients, and local strain rates, is preliminarily discussed. Further theoretical analyses are conducted to investigate the movement of the diffusion fronts. It is of significant reference for understanding the dynamic failure mechanism of brittle granular matter.

Development of an adaptive CTM–RPIM method for modeling large deformation problems in geotechnical engineering

In this paper, a meshfree method called adaptive CTM–RPIM is developed to model geotechnical problems with large deformation. The developed adaptive CTM–RPIM is a combination of the Cartesian transformation method (CTM), the radial point interpolation method (RPIM) and the alpha shape method. To reduce the requirement for meshes, the CTM is adopted to transform domain integrals into line integrals, and the RPIM is applied to construct interpolation functions. The alpha shape method, which is capable of capturing severe boundary evolution due to large deformations, is then introduced into the CTM–RPIM to form the adaptive CTM–RPIM. The accuracy of CTM–RPIM is first verified by considering a cantilever beam under small deformation, where the influence of key parameters on the simulation results is explored. Afterward, the ability of the adaptive CTM–RPIM to handle large deformation problems is demonstrated by simulating cantilever beams with large deformations for which analytical solutions are available. Finally, the ability of the proposed method to model the geotechnical large deformations is illustrated from both quasi-static and dynamic aspects, where a slope failure problem and a footing bearing capacity problem are modeled to evaluate the stability of geotechnical structures; and a 2-D soil collapse experiment using small aluminum bars is simulated to show the method capability in describing the soil flows. These benchmark examples demonstrate that the adaptive CTM–RPIM is a numerical method with broad application prospects for modeling large deformation problems in geotechnical engineering.

Effect of acoustic load on electromechanical characteristics of sandwiched piezoelectric ultrasonic transducers in broken rail detection

This article investigates the effect of acoustic load on electromechanical characteristics of sandwiched piezoelectric ultrasonic transducers in time and frequency domains. The acoustic load includes aluminum and steel bars. It is shown that when the length of the acoustic load satisfies positive integer multiple of half-wavelength, the first resonant frequencies generate a smaller increase. With the increase of the length and characteristic impedance of acoustic load, the first resonant frequencies, and the tailing length of the received signal are increased, while the receiving signal amplitude, effective electromechanical coupling coefficient, and mechanical quality factor are decreased.

Feasibility Study of an Active Sensing Approach to Detect Soil Slope Interlayer Slide Using Piezoceramic Buzzers

For soil slope, interlayer slide along the soil-rock interface is the precursor and cause of large-scale landslide disasters. Deep stability status in the slope body is crucial and has always been highly valued in geotechnical engineering. Real-time monitoring of soil-rock interface and early warning of landslide disaster is of great importance for landslide disaster prevention, mitigation and relief. In order to explore the evolution process of the soil-rock interface from stability to slippage, a physical model test at conventional gravitational acceleration condition was performed in laboratory. In this study, an innovative active sensing approach based on four piezoceramic buzzers that attached on an aluminum bar was proposed to detect the soil slope interlayer slide. Among the four buzzers, one was employed as an actuator to generate stress wave, while other three were acted as sensors to receive the propagated signals. The installation of transducers, fabrication of the slope model and monitoring system were presented in detail. During the test, a horizontal thrust was applied on the trailing edge of the slope model using a hydraulic jack. The interlayer slide behavior was then carefully monitored by the propagated stress waves. It was found that the measured stress waves in both time and frequency domain had a negative correlation with the slope sliding distance. It can be attributed to that the interlayer slide attenuates wave energy and then decreases the signal intensity. Additionally, a wavelet packet analysis was employed to develop a slope slide index to evaluate the soil-rock interlayer slide. Experimental results demonstrated that the proposed method is novel yet effective for soil slope interlayer slide monitoring.

Determination of the high-strain rate elastic modulus of printing resins using two different split Hopkinson pressure bars

The usage of resin-based materials for 3D printing applications has been growing over the past decades. In this study, two types of resins, namely a MMA-based resin and an ABS-based tough resin, are subjected to compression tests on a split Hopkinson pressure bar to deduce their dynamic properties under high strain rate loading.Two Hopkinson bar setups are used, the first one is equipped with aluminum bars and the second one with PMMA bars. From the measured strain waves, elastic moduli at high strain rates are derived. Both setups lead to values of E=3.4–3.8 GPa at a strain rate of about 250 s−1. Numerical simulations support the experiments. Moreover, considering the waves gained from the two different bar setups, PMMA bars appear to be well-suited for testing resin samples and are therefore recommended for such applications.

A customizable aluminum compensator system for total body irradiation.

PurposeTo develop a simplified aluminum compensator system for total body irradiation (TBI) that is easy to assemble and modify in a short period of time for customized patient treatments.MethodsThe compensator is composed of a combination of 0.3 cm thick aluminum bars, two aluminum T‐tracks, spacers, and metal bolts. The system is mounted onto a plexiglass block tray. The design consists of 11 fixed sectors spanning from the patient's head to feet. The outermost sectors utilize 7.6 cm wide aluminum bars, while the remaining sectors use 2.5 cm wide aluminum bars. There is a magnification factor of 5 from the compensator to the patient treatment plane. Each bar of aluminum is interconnected at each adjacent sector with a tongue and groove arrangement and fastened to the T‐track using a metal washer, bolt, and nut. Inter‐bar leakage of the compensator was tested using a water tank and diode. End‐to‐end measurements were performed with an ion chamber in a solid water phantom and also with a RANDO phantom using internal and external optically stimulated luminescent detectors (OSLDs). In‐vivo patient measurements from the first 20 patients treated with this aluminum compensator were compared to those from 20 patients treated with our previously used lead compensator system.ResultsThe compensator assembly time was reduced to 20–30 min compared to the 2–4 h it would take with the previous lead design. All end‐to‐end measurements were within 10% of that expected. The median absolute in‐vivo error for the aluminum compensator was 3.7%, with 93.8% of measurements being within 10% of that expected. The median error for the lead compensator system was 5.3%, with 85.1% being within 10% of that expected.ConclusionThis design has become the standard compensator at our clinic. It allows for quick assembly and customization along with meeting the Task Group 29 recommendations for dose uniformity.

Determination of Wound Healing Activity of Shark Liver Oil using Burn Wound Model in Wistar Rats

<p style="text-align: justify;"><strong>Background:</strong> Research on wounds has proved that a wound instigates interruption to skin integrity caused by physical trauma or disease. Burn is a wound which causes tissue coagulant necrosis and thus exerts a devastating effect on individuals in terms of human health and injury. The present study is designed to evaluate wound healing properties of Shark liver oil and estimate various parameters such as, SOD, CAT, GSH, hydroxyproline and histopathological studies.<strong> Methods: </strong>Thermal injuries were done with a solid aluminum bar 10 mm in diameter formerly heated in boiling water to facilitate the temperature reached 100&deg;C measured with a thermometer. Ketamine at a dose of 80 mg/kg is given to produce anesthesia and the hair on dorsum of rats were shaved to ensure even burn wounding. From day-1 to end of experiment (30 days), these rats were applied with Standard (Silver Sulphadiazine Ointment USP 5% w/w) and SLO (Shark liver oil emulgel, 5%, 10% and 15%) formulations were applied 1 mg/cm²; topically. Animals were subsequently examined for biochemical and histopathological variations. <strong>Results: </strong>In burn wound model the developed shark liver oil emulgel shows significant wound healing property in dose dependent manner as compare to disease control groups. The wound healing property of shark liver oil emulgel 5%, 10% and 15% (*<em>p</em>&lt;0.05, **<em>p</em>&lt;0.01) showed wound healing on 3^rd and 4^thweek respectively. <strong>Conclusion:</strong> The shark liver oil emulgel exhibited significant wound healing activity in burn wound model, comparable to the marketed standard formulations. This finding provides an insight into the usage of the shark liver oil emulgel in the treatment of wounds or burns. <p style="text-align: justify;"><strong> Key words: </strong>Burn wound, Percentage wound closure, Hydroxyproline, Epithelization, Shark liver oil and Wound healing activity.

Numerical modelling of interaction between aluminium structure and explosion in soil

In this paper, a graphics processing unit-accelerated smoothed particle hydrodynamics solver is presented to simulate the three-dimensional explosions in soils and their damage to aluminium structures. To achieve this objective, a number of equations of state and constitutive models required to close the governing equations are incorporated into the proposed smoothed particle hydrodynamics framework, including the Jones-Wilkins-Lee equation of state for explosive materials, the Grüneisen equation of state for metals, the elastic-perfectly plastic constitutive model for metals, and the elastoplastic and elasto-viscoplastic constitutive models for soils. The proposed smoothed particle hydrodynamics methodology was implemented using the Compute Unified Device Architecture programming interface on an NVIDIA graphics processing unit in order to improve the computational efficiency. The various components of the proposed methodology were validated using four test cases, namely, a C4 detonation and an aluminium bar expanded by denotation to validate the modelling of explosion, a cylindrical Taylor bar impact test case to validate the modelling of large deformation in metals, a sand collapse test for the modelling of soils. Following the validation, the proposed method was used to simulate the detonation of an explosive material (C4) in soil and the concomitant deformation of an aluminium plate resulting from this explosion. The predicted results of this simulation are shown to be in good conformance with available experimental data. Finally, it is shown that the proposed graphics processing unit-accelerated SPH solver is able to model interaction problems involving millions of particles in a reasonable time.

Investigation on modulation of multi-frequency ultrasonic waves in structures with quadratic nonlinearity

In this study, the modulation of multiple frequency content of a single ultrasonic wave in nonlinear structures is investigated analytically, numerically and experimentally. An experimental technique is proposed based on nonlinear lamb wave propagation in aluminum bars using piezoelectric wafer active sensors (PWAS) to study intrinsic nonlinearity of structures. First, a one-dimensional analytical procedure is developed to study the modulation of one dimensional wave with multiple-frequency content in isotropic medium with quadratic nonlinearity. This procedure is implemented to study modulation of frequency contents of a well-known tone burst signal in nonlinear medium. Then, predictions obtained by the proposed analytical procedure are compared with the results of finite element model, which show strong correlations. The experimental and analytical results reveal that in excitation with a train of tone burst, due to frequency modulation, some new harmonics including a strong sub harmonic generation with frequency of f0/Np appear in the response. The amplitude of this harmonic is even higher than common second harmonic generation (2f0). This can be seen in the experimental results when the excitation frequencies are correctly selected. Finally, it is explained that, why the new sub harmonic generation is less affected by the nonlinearity induced by the excitation system.

Treatment of Al-Muthanna Petroleum Refinery Wastewater by Electrocoagulation Using a Tubular batch Electrochemical Reactor

An electrocoagulation process has been used to eliminate the chemical oxygen demand (COD) from wastewaters discharged from the Al-Muthanna petroleum refinery plant. In this process, a circular aluminum bar was used as a sacrificial anode, and hallow cylinder made from stainless steel was used as a cathode in a tubular batch electrochemical Reactor. Impacts of the operating factors like current density (5-25mAcm-2), NaCl addition at concentrations (0-2g/l), and pH at values (3-11) on the COD removal efficiency were studied.Results revealed that the increase in current density increases the COD removal efficiency, whereas an increase in NaCl concentration results in a decline in the COD removal efficiency. Using a pH value higher or lower than 7 causes a lowering of the COD removal efficiency. A current density of 15mA/cm2, NaCl concentration of 1g/l, and pH value of 7 were found to be the best operating conditions in which COD removal efficiency of 95.3% was achieved at a treatment time 45 minutes with an energy consumption of 27.78kWh/kg COD. Based on these conditions, a COD value of 20 ppm could be obtained, which is below the standard limit for discharging petroleum refinery effluents.

Therapeutic effect of mesenchymal stem cells on histopathological, immunohistochemical, and molecular analysis in second-grade burn model

Background and aimDeleterious cutaneous tissue damages could result from exposure to thermal trauma, which could be ameliorated structurally and functionally through therapy via the most multipotent progenitor bone marrow mesenchymal stem cells (BM-MSCs). This study aimed to induce burns and examine the effect of BM-MSCs during a short and long period of therapy.Material and methodsNinety albino rats were divided into three groups: group I (control); group II (burn model), the animals were exposed to the preheated aluminum bar at 100°C for 15 s; and group III (the burned animals subcutaneously injected with BM-MSCs (2×106 cells/ ml)); they were clinically observed and sacrificed at different short and long time intervals, and skin samples were collected for histopathological and immunohistochemical examination and analysis of different wound healing mediators via quantitative polymerase chain reaction (qPCR).ResultsSubcutaneous injection of BM-MSCs resulted in the decrease of the wound contraction rate; the wound having a pinpoint appearance and regular arrangement of the epidermal layer with thin stratum corneum; decrease in the area percentages of ADAMs10 expression; significant downregulation of transforming growth factor-β (TGF-β), interleukin-6 (IL-6), tumor necrotic factor-α (TNF-α), metalloproteinase-9 (MMP-9), and microRNA-21; and marked upregulation of heat shock protein-90α (HSP-90α) especially in late stages.ConclusionBM-MSCs exhibited a powerful healing property through regulating the mediators of wound healing and restoring the normal skin structures, reducing the scar formation and the wound size.

The Application of WSM, WPM and WASPAS Multicriteria Methods for Optimum Operating Conditions Selection in Machining Operations

Optimal condition selection in machining operations is an imperative decision for the process engineer as it influences improved tool life and surface roughness values. As the aluminium market is extremely competitive, process engineers strive to understand what to do to gain preference from prospective customers. From this viewpoint, the criteria responsible for operating decisions should be examined. In this paper the WSM, WPM and WASPAS multicriteria methods are proposed for optimal machining conditions for turned aluminium bars. A stepwise methodology of the WSM, WPM and WASPAS methods is detailed. The proposed technique was tested on published data regarding the turning of an aluminium bar, machined on a lathe machine. The case study consists of three input parameters (spindle speed, feed rate and depth of cut) and four responses (cutting temperature, cutting force, surface roughness and material removal rate). After analysing the experimental data using the models, the entropy method chose material removal rate was chosen as the best. Using the three other models, the best selection was run 17 which correspond to an input parameter of 605 rpm spindle speed, 0.12 mm/rev feed rate and 1.8 mm depth of cut. This article offers a completely new approach to operating condition selection in the turning of the aluminium bar. In the current aluminium market, it is extremely important to understand the operating conditions of the machine for enlarged customer patronage and sustainability. The unique feature of this approach is the elevated level of reliability it exhibits.

Tuning idiophone bar torsional modes with three-dimensional cutaway geometries

The bars of marimbas, vibraphones and similar idiophones are tuned by shaping their “cutaway” or “undercut” geometries. Makers commonly shape bar cutaways to tune three flexural modes of vibration. The first flexural mode is tuned to the fundamental frequency of the bar’s musical note. Two other flexural modes are tuned such that their frequencies become specific multiples of the fundamental. The remaining flexural modes and all other modes are left untuned. Makers have complained of untuned torsional modes polluting bar timbre over specific sections of the keyboard. In wooden marimba bars this problem has proven difficult to predict, filling reject bins with valuable tonewood. This work investigates tuning these torsional modes by varying bar cutaway geometry in three dimensions. No additional mass or heterogeneous materials are employed. Modal frequencies are determined via finite element analysis. Mode shapes are identified algorithmically, enabling analyses to explore the parameter space unsupervised. Geometries are tuned using a gradient-based search method. The approach, designed to efficiently solve underdetermined systems with multiple objectives, is readily applicable to other problems. A selection of tuned example models will be showcased, including rosewood and aluminum bars with common and uncommon tuning ratios.

Heat transfer, physiological responses, and subjective perceptions during short contact time with wood or other materials

This study investigates the physiological responses and subjective perceptions of touching wood. In particular, it focuses on their respective relationships with the amount of heat transfer across the hand–material interface during contact. The study participants included 55 university students (20 females and 35 males) who gave written informed consent. The participants’ blood pressure, pulse rate, and cerebral blood hemoglobin concentrations were measured continuously for 90 s while they gently held vertical bar-shaped specimens of Japanese cypress (Chamaecyparis obtusa), Japanese oak (Quercus crispula), polyethylene, and aluminum. The specimens also included wood with a surface coating. We measured subjective warmth and comfort as well as the heat flux between the palm and the surface of the material. The wooden materials were rated as significantly warmer compared to aluminum and polyethylene, regardless of the wood species (cypress or oak) or its coating; this result corresponds with smaller heat transfers in the wooden materials. Additionally, the wooden materials were more comfortable to hold as compared to the aluminum bar. Based on the changes in blood pressure, touching Japanese cypress and uncoated Japanese oak were interpreted to induce less physiological stress. Therefore, we can conclude that wood, with lower thermal conductivity, feels warm, and it causes relatively smaller physiological changes compared to other materials with higher thermal conductivity. Thus, they may present less physiological burdens when touched.

Understanding the process of making fuse contacts by upsetting of aluminium bars

This paper describes the results of a study that looked at an innovative wastefree process of cold upsetting to make power fuse contacts from the commercial aluminium grade AD1. The process involves upsetting and extrusion of a workpiece cut from steel bar stock in the same die in one process step. It is proposed to use this process instead of making each separate fuse contact part, i.e. when the fuse base and the knife are notched out of a steel bar and are then stamped together. The new process is less labour intensive due to less pieces of die tooling used, less equipment required, less personnel involved and due to a significantly higher metal utilization factor – 1 instead of 0.7. Solid models have been developed for the solid part of fuse contact and for the die tooling so that this process could be performed in a die. A procedure has been developed for making fuse contacts by cutting a steel bar in the die with a flat end punch followed by upsetting and extrusion of the workpiece. The dimensions of the primary blank and the forces acting at different process steps have been determined. The upper-bound method was applied to conduct a theoretical study of kinematic parameters and forces involved in the process. Physical and mathematical modelling helped establish how a steel bar changes its shape under upsetting and extrusion. Having analyzed the block models of the extrusion process with kinematically possible velocity fields, the authors identified what conditions lead to defect formation and offered some measures to prevent such defects. Force-geometry relationships have been defined. Experimental die tooling has been made and a prototype die – designed to implement this process in practice. A pilot batch of fuse contacts has been produced.