Self-made Device Research Articles

Rotational regimes of freely suspended liquid crystal films under electric current in presence of an external electric field

The electrohydrodynamic (EHD) vortices produced by an electric current in freely suspended liquid crystal (LC) films of N-(4-methoxybenzylidene)-4-butylaniline (MBBA), convert to a pure rotation in the presence of external electric field (\(\it{E}_{{\rm ext}}\)) perpendicular to the current direction. Here, the direction and strength of the rotation are precisely under control by our self-made device called “liquid-film motor”. In this paper, we present experimental observations of the EHD fluid flow when external electric field varies from zero to a value in which pure rotation on the liquid crystal (LC) film is observed. We also show experimentally that the presence of external electric field causes a great decrease in the current produced by the voltage VJ required for observing EHD vortices in freely suspended films of MBBA. The LC films begin to rotate when EextVJ reaches a threshold value. This threshold is investigated experimentally as a function of voltage VJ and the external electrical field \(\it{E}_{{\rm ext}}\).

Study on Polymer Powder Solid Extrusion Forming

Engineering plastics has many uses, such as national defence, communication and scientific research. In this paper a new experiment plan was proposed in order to get a new engineering plastics forming method. Through the compressive test of polyoxymethylene powder, the process parameters such as temperature, stress and velocity are obtained.Based on the parameters got from compressive test polyoxymethylene powder solid extrusion forming was studied by self-made device. Microscopic analysis and mechanical properties test show that the process parameters are reasonable, the crystallinity increase and molecular chain is oriented along the extrusion direction, as a result the tensile strength and modulus increase greatly.

Comparison on the Adsorption Thermodynamics of Three Typical Petroleum Hydrocarbons in the Single and Mixed Solution on Aquifer Media

This paper researched on the adsorption kinetics and thermodynamics of the typical components of petroleum hydrocarbon-benzene, naphthalene, phenanthrene and their mixed solution on the typical media-the medium sand from the aquifer in an oil contaminated field, with a self-made rotary adsorption device. The result showed that the adsorption of the three adsorbates on the media follows the Henry adsorption model, no matter when they are separated or mixed. The adsorption capacity order of benzene, naphthalene and phenanthrene on the medium sand is phenanthrene> naphthalene>benzene, when they are separated or mixed. Comparing with the adsorption capacity when the adsorbates are single, benzene and naphthalene in the mixed solution shows stronger adsorption capacity, while phenanthrene carries on less adsorption capacity.

Comparison Experiments on Relieving Differential Settlement of Subgrade by Graded Crushed Rock in Different Particle Sizes

By the self-made experimental device, the experiment research on the role of relieving differential settlement of subgrade on graded crushed rock in different particle sizes has conducted. The experiment has tested the stress of central, edge and corner of the slab when cavity is produced. The experiment results show that, the graded crushed rock is able to better correspond differential settlement deformation of the subgrade, the liquidity of the bulk particle can fill the cavity spaces. The stress in the slab increases with the addition of the cavity height and the loading. The graded crushed rock with different particles plays different roles on the relief effect of cavity. Generally speaking, the effect of the graded crushed rock in 31.5mm size is better than that of in 19mm size.

Preparation of hybrid ion channel membrane for recognizing and transporting sodium ion

A kind of self-organized hybrid material, 3-(ureidobenzene) propyltriethoxysilane, was obtained from 3-isocyanatopropyltriethoxysilane and aminobenzene with chloroform as solvent. The structure and the morphology of the materials were characterized by FTIR, 1H-NMR, and XRD methods. The ion channel membrane was obtained by coating the hybrid material onto the commercial polyacrylonitrile (PAN) supports via sol-gel process. The chemical structure and surface morphology of the membrane was characterized by ATR-FTIR and SEM separately. The ion transport property of the membrane was tested by our self-made device with the conductivity. SEM showed that the surface of ion channel membrane was dense and thickness of the dense layer was about 8.5 &mgr;m. The transport experiment suggested that the membrane had the properties of recognizing and transporting Na+.

Internal relative humidity and creep of concrete with modified admixtures

AbstractThe creep characteristics and internal relative humidity (IRH) of concrete with shrinkage reducing admixtures (SRA), poly vinyl alcohol fiber (PVAF) and a mixture of fly ash and slag (MFS) were investigated by the self-made loading device. The pore structure was tested, and the relationship of creep and IRH of concrete was discussed. The results indicate that MFS and SRA reduce the total creep and delay the change of IRH. However, the effect of PVAF is contrary, relative to MFS and SRA. The total creep depends largely on drying creep. The basic creep of concrete is similar, which is significantly influenced by volume fraction of pores whose diameter is between 3.5 nm and 50 nm to the total pore (VP), and IRH of concrete is connected with porosity. It is easy to obtain a good linear relationship predicting the creep of concrete according to the change of IRH.

The effects of vibration field on crystal structures and orientation of isotactic polypropylene injection samples

In this study, isotactic polypropylene (iPP) samples were prepared by self-made pressure vibration injection device, in which a periodical shear field was imposed on the iPP melt during the filling and packing stages. The crystal structures and orientation of samples were investigated by wide-angle X-ray diffraction and polarizing light microscopy (PLM). The β form and γ form were found in vibration injection molding samples. Compared with the static samples, the orientation of iPP chains within lamellae was observed in the transition layer (at the depth of 1.5 mm from the surface) of the vibration injection molding samples, and the orientation was found even in the core layer. The PLM observation indicates the β form exists in the transition and core region of the vibration sample. Besides, two types of β-PP could be observed simultaneously in the core region under high magnification. The bright β crystallites (βIII) are fan-shaped and lie perpendicularly to the flow direction. In the other hand, the ringed β crystallites (βIV) almost remain their spherulite shape. Moreover, fiber crystal was observed in vibration sample, even in the core region. Some fiber crystals in the transition region reappeared in the cooling circle after the sample was held at 180 °C for 2 min. This could be explained in structure memory effect and its high thermal stability.

Modification Mechanism of the ZTA Ceramic Powders with Stearic Acid

In this study, ZTA powder is modified by SA with different concentrations (0wt%, 1wt%, 2wt%, 3wt%, 4wt%) for the purpose of improving its properties. The effects of SA on microstructure, particle size distribution and flowability of the ZTA powder are investigated by scanning electron microscope(SEM), laser diffraction analyzer and self-made testing device of the angle of repose. After treatment, the average diameter of the powder decreases, the powder shows better dispersibility and flowability especially when the content of SA is 3wt%. FTIR spectroscopy is employed to evaluate the effect of SA coating on ZTA powder. The results indicate that a covalent bond is formed by the reaction between the hydroxyl group of ZTA surface and carboxyl group of stearic acid. Moreover, the changing of the polarity of ZTA powder can result in a stable dispersion in organic solvents.

Research on the Effect of Ultrasonic Impact Peening on the Fatigue Property of 7075-T651 Aluminum Alloy

The fatigue property of friction stir welded joints in Ai7075-T651 is crucial adjective in the modern aerospace industry. Treated by the UIP (Ultrasonic impact peening) process using the self-made device, the effects are studied in this paper, and the results show that: under the stress ratio R=0.5, the fatigue life of welded joints treated by ultrasonic peening is prolonged by 8~14 times. The strengthened layer caused by the plastic variation, surface hardening and uniformity of tissue, and transversal residual stress of base metal after UIP becomeing compressive residual stress of 100 Mpa in the surface, which are the main reasons that lead to the improvement of fatigue property.

Design and analysis of the precision-driven unit for nano-indentation and scratch test

This paper presents a kind of precision-driven unit consisting of the piezoelectric actuator and flexure hinge to realize precision motion of the indenter in a self-made indentation device. Two important parameters of the flexure hinge, thickness t and width w, were analyzed via finite element method and the results showed that the output displacement was a monotonic decreasing function of thickness t and width w. The stiffness was a monotonic increasing function of thickness t and width w. But almost all the first-order modal frequencies of flexure hinges with different thickness t and width w were higher than 3800 Hz which indicated that flexure hinges had good stability at low frequency condition. Output performance of the unit was tested and analyzed. Experimental results showed that the average maximum output displacement was 12.88 μm when the voltage was 120 V and the resolution was about 0.537 μm/V. The hysteresis was very small and it was about 8.91%. At last, the designed unit was assembled on a self-made indentation device. Preliminary indentation experiments proved that the unit worked well. So, the piezoelectric mechanism can be used in the indentation device and it is beneficial to ensure the miniaturization and realize in situ indentation experiments in the SEM and TEM.

Experimental Study of Micro Deep Drawing for H62 Brass

In this paper, the influence of grain size and blank hold force on micro deep drawing stress and displacement are studied by self-made device. The results show that drawing stress decreases and elongation rate increases with the increase of grain size, the concentrated force area of cylinder-shaped part is transferred from the area punch fillet to die fillet area. Twin grain ratio and twinning degree near the punch fillet are increasing. Twin grain distribution becomes uneven with the increase of grain size. In micro deep drawing, the displacement increases with the increase of blank hold force, meanwhile, forming stress almost remains constant. The flange wrinkling can be inhibited.

Effects of Heat Shrinkage on Structure and Property of Silk/Synthetic Fiber Textured Composite Filaments

The textured yarn was respectively prepared with pure silk, silk/polyester POY composite filament, silk/polyester FDY composite filament by the self-made processing device. The effects of heat shrinkage of polyester fibers on the structure and properties of the textured filaments were investigated. The results revealed that silk/POY composite filament contained higher heat shrinkage. Synthetic fibers produced crimps with larger amplitude and smaller bandwidth, and the textured filaments presented a larger yarn count, resulting in the notable crimped deformation.

Study on Evaluation of Woven Garment Stitch Crack

A variety of stress cracks appear in the garment seam, which affects the appearance and the seam strength. In this paper, the indicating methods of seam cracks were presented by identification and analysis of a variety of seam cracks on woven garments. The regression equation of seam crack recognizable rate was listed through different kinds of seam cracks observed and distinguished by inspectors. The influence on crack recognizable rate by the size and the colour of the crack was also analyzed in this paper. The objective assessment of fracture strength was made by testing the fracture strengths of five kinds of fabrics in warp, weft and 45 ° oblique direction using self-made needle crack testing device. This paper has certain significance for fabric designing and clothing production technology.

Protective effect of biodegradable ureteral stent on renal function after traumatic ureter injury

Objective To establish a new canine model of ureter trauma to observe the protective effect of biodegradable ureteral stent on renal function following traumatic ureter injury. Methods A self-made device was used to make firearm fragment wounds unilaterally on the ureters in nine Beagle dogs （model group）. The wounds were debrided and sutured and the results were evaluated by using intravenous pyelography （IVP） and radioactive renography at 40, 80 and 120 days postoperatively. Firearm fragment wounds were made to the bilateral ureters of nine Beagle dogs in the positive control group, in which a biodegradable stent was placed in one side and a double-J stent placed in the other side. Results In model group, hydronephrosis and hydroureter occurred and got worse postoperatively on the wounded side in all nine Beagle dogs, while none of these symptoms were found in any animals in the control group. The ratios of biodegradable stent side to double-J stent side were increased in renal patial concertration index and half time of kidney washout, but neither showed significant differences. However,vesicoureteral reflux （VUR） was not found in the biodegradable stent side, but in the double -J stent side. Conclusions A new canine model of firearm fragment wounds is successfully developed. Both the biodegradable and double-J stent play important roles in support and drainage and show no significant difference in aspects of renal uptake and half time of kidney washout. The biodegradable stent can effectively prevent VUR. Key words: Firearms; Ureter; Stents; Vesico-ureteral reflux

Experimental Study on the Characteristics of Surface Roughness in Ultrasonic Aided High-Speed Lapping of Engineering Ceramics

The surface roughness of machined surface is one of the important indicators to evaluate the workpiece machining quality. In order to clarify the change law of surface roughness in ultrasonic aided high-speed lapping with solid diamond abrasive, a series of ultrasonic and conventional lapping experiments of different engineering ceramics, such as Al2O3, ZrO2 and ZTA, were carried out on precision lathe with self-made high-speed ultrasonic lapping device. The research results show that the value of surface roughness in ultrasonic aided lapping is lower than that in conventional lapping. With the assistance of ultrasonic vibration, the surface quality can be improved obviously. In ultrasonic aided lapping, there is an optimum lapping pressure from which a better surface roughness value can be obtained. Because of different physical and mechanical properties, material removal mechanisms of the three kinds of engineering ceramics present different characteristics, which lead to the different surface roughness even though under the same lapping conditions. The research of the paper is helpful to optimize lapping technique and improve the surface quality.

Erosion–corrosion of thermally sprayed coatings in simulated splash zone

The damage of marine steel structures in the splash zone is very severe. Applying thermally sprayed metal coatings is among the most important protective technologies, but the service life of current coatings is limited. In this paper, arc spray was used to prepare four types of metal coatings, that is, aluminum (Al), zinc bottom coating combined with aluminum topcoat (Zn+Al), aluminum–zinc pseudo alloy (Al/Zn) and aluminum–titanium pseudo alloy (Al/Ti) coatings. These metal coatings were sealed with epoxy priming and aliphatic polyurethane topcoat. Erosion–corrosion experiments were carried out on self-made device by simulating the splash zone working environment of steel structures and protective coatings. The results show that all the sealed coatings could improve the steel resistance to erosion–corrosion, and the aluminum–zinc pseudo alloy is the most excellent coating. In the coating failure process, mechanical erosion rather than corrosion is the key factor causing coating erosion–corrosion in splash zone. Improving the anti-cutting properties could help to prolong the coating life.

Determination of volatiles released from plants by the self-made charcoal trap adsorption device coupled with gas chromatography-mass spectrometry

The charcoal trap adsorption device was designed and used to adsorb the volatile organic compounds (VOCs) emitted from Ginkgo leaves and Lima beans. The adsorbed VOCs were determined using gas chromatography-mass spectrometry (GC-MS). Compared to solid phase microextraction (SPME), the self-made charcoal trap adsorption device was more advantageous to the enrichment of VOCs from Ginkgo leaves. Additionally, the quantitative analysis of the collected VOCs released from Lima beans was carried out through the addition of internal standard, and the results of the two parallel experiments showed good repeatability. Because the eluent of the charcoal trap can be stored and used in the quantitative analysis as well as parallel experiments, the self-made charcoal trap adsorption device coupled with GC-MS is suitable for laboratory studies of plant volatile organic compounds.

Preparation and characterization of high‐temperature resistance polyimide foams

AbstractA new high‐temperature resistance polyimide foam was synthesized from 2,3,3′,4′‐biphenyltetracarboxylic dianhydride (α‐BPDA) and p‐phenylenediamine (p‐PDA). The structures and foaming process of polyimide precursor powders were characterized by wide‐angle X‐ray diffractometer (WXRD) and the self‐made visualization device, respectively. The imidization degree, thermal mechanical properties and thermal stability of the polyimide foams with different post‐treatment temperatures were also measured by fourier transform infrared spectrometer spectrum (FTIR), dynamic thermal mechanical anaylsis (DMTA), and thermogravimetric analysis (TGA). Results showed that the inflation onset temperatures of polyimide precursor powders ranged from 122 to 135°C with varying the heating rate. And the increase in the imidization degree, glass transition temperatures (Tg) and temperatures for 5 wt% mass loss of high‐temperature resistance polyimide foams can be achieved with increasing post‐treatment temperature. It was quite surprising to find that Tg of high‐temperature resistance polyimide foam post‐treated at 420°C was up to above 450°C, and the char yield at 800°C was more than 60%. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

Roles of Pumps and Bypass in Chemistry Induced by Hydrodynamic Cavitation

AbstractIn this investigation, a self‐made low pressure device (up to 100 psi) for creating hydrodynamic cavitation was optimized by using the Weissler reaction. Optimal upstream pressure for the reaction was obtained for a single line system (without bypass) as 29 psi. The effects of the centrifugal pump and the bypass were significant as compared with the effect of the restrictions investigated. Therefore, the use of more lines is proposed. The effects of different restrictions (valve, one‐hole plate, and multi‐hole plate) were investigated and multi‐hole plates show better efficiency.

Percutaneous transtracheal emergency ventilation with a self‐made device in an animal model

Special equipment for emergency percutaneous transtracheal ventilation is often not immediately available. We used a self-made device consisting of a three-way stopcock connected between a G-15 transtracheal airway catheter and an oxygen supply in a simulated 'cannot intubate, cannot ventilate' scenario and tested the hypothesis that the effectiveness of the device depends on the body weight of the experimental animals. With approval of the local animal protection committee, two groups of six pigs each with a body weight of 21 +/- 2 and 36 +/- 6 kg, respectively, were tracheally intubated and mechanically ventilated after induction of anesthesia. Hemodynamic monitoring included cardiac output and arterial, central venous and pulmonary artery pressures. An emergency transtracheal airway catheter was inserted into the trachea and a situation of partial expiratory airway obstruction was created. Each animal was ventilated for 15 min via the transtracheal airway catheter with the self-made device (FiO(2) 1.0 at an oxygen flow of 15 l x min(-1); respiratory rate of 60 min(-1); I/E ratio approximately 1:1). Whereas satisfactory oxygenation was achieved in all animals, sufficient ventilation was obtained only in the lightweight animals. Adequate oxygenation could be provided by jet-like transtracheal ventilation with a simple self-made device using easily available materials. Sufficient ventilation depends on the body weight of the animals.