Opening Radius Research Articles

Numerical Investigation of High-temperature Molten Salt Leakage

Abstract As molten salt has been widely used in solar thermal power and nuclear power system, its leakage was an important problem. In this paper, the high-temperature molten salt leakage is simulated by considering the effects of phase change and flow dynamics. During the molten salt leakage process, the liquid molten salt is cooled by the ground and air, so it will solidify, and then a thin solidification layer of molten salt forms. The whole high-temperature molten salt leakage process consists of three subprocesses: spreading process, stable solid front formation process and solidification process after leakage. According to the simulation result, the radius of the leakage opening mainly affects the radius of nitrate solidification layer, while the leakage temperature and the leakage velocity will influence both the radius and thickness of salt layer. Besides, different kinds of molten salt are also considered, and the radius of molten salt solidification layer with SYSU-N1 is smaller than that with Solar Salt.

Analysis of Nuclear Track Parameters of CN-85 Detector Irradiated to Thermal Neutrons by Using MATLAB Program

CN-85 detector which covered with boric acid H3Bo3 pellete has been irradiated by thermal neutrons from (241Am-9Be) source with activity 12 Ci and neutron flux 105 n. cm-2. s-1. The irradiation times-TD for detector were 4 h, 8 h, 16 h and 24 h. The track detector has been etched with sodium hydroxide. After chemical etching of the irradiated CN-85 detector, the images have been taken from a digital camera connected to the optical microscope. Image processing for the output images has been performed using MATALB program, and these images were analyzed and we had found the following relations: a) The relation between summation of opened track or surface density for tracks (intensity-IT) varies with radius of opening (track radius-RT). b) The relation between the tracks number-NT varies with the tracks diameter-DT (in micrometer) and tracks area-AT. That analysis of image processing was obtained, and the track intensity-IT was decreased with increase of track radius-RT at all of the irradiation time-TD. And the track intensity-IT was increased with increasing irradiation time-TD (h) for different track radius-RT (0.4225, 0.845, 1.2675 and 1.69 μm). The study indicates the possibility of using the analysis of image processing to CN-85 detector for classification of α-particle emitters through limitation of radius of track-RT, in addition to the contribution of these techniques in preparation of nano-filters and nono-membrane in nanotechnology fields.

Water Sorption and Hindered Diffusion with Different Chain Stiffness of Superabsorbent Polymer

Water sorption and diffusion are essential physicochemical properties of a high‐performance superabsorbent polymer (SAP). We combine the Park model with the obstruction‐scaling model and the water clustering in confined spaces of the polymer hydrogel. Special attention is focused on elucidating the effect of chain stiffness by considering the conformation of the polymer chain. Theoretical model parameters are determined from the best fits by simultaneous nonlinear regressions for both sorption and corrected diffusion data based on previous experiments with poly(acrylamide‐co‐sodium acrylate) hydrogel. Predictions show that the hindered water diffusivity leads to a sigmoid curve with relative humidity aw, where it increases monotonically up to aw ≈ 0.6 due to the swelling but decreases at higher aw caused by water clustering. Water diffusion decreases with increasing chain stiffness, and the larger persistence length provides a smaller opening radius in void spaces regarding the weak elastic deformation of hydrogel under the applied stress.

Experimental Study of Characteristics of Flow over Weirs with Semicircular Openings

In this research, an experimental investigation was conducted to study the characteristics of flow over weirs with semicircular openings. Four radii of the weir openings were used and three crest heights with either a sharp or semi- circular shape for each radius. The results show that for the same crest height and the same depth of water over the crest, the discharge passing over the weir increased with the in- creasing radius of the semicircular opening. Also, for the same radius of the weir opening and the same depth of water over the crest, the discharge passing over the weir increased with the increasing crest height. For measuring the actual discharge over the weirs with semicircular openings, a new and reliable empirical equation was developed for the weirs with sharp crests and another one for weirs with semicircular crests.

Numerical Investigation of Nitrate Leakage and Migration in the Soil after Rainfall

Nitrate salt is important heat transfer and storage medium in solar thermal power system, but nitrate salt leakage and pollution in groundwater is seldom investigated. In this paper, the nitrate salt leakage and migration in the soil after rainfall are simulated and analyzed. During the nitrate leakage process, the liquid nitrate will solidify, and then a thin solidification layer of nitrate forms. According to the simulation result, the radius of the leakage opening mainly affects the radius of nitrate solidification layer, while the leakage velocity will influence the radius and thickness of salt layer. During the nitrate migration process after rainfall, the nitrate will gradually migrate to the groundwater, and the final migration domain of nitrate in the soil will be mainly determined by the radius of nitrate solidification layer.

Thermal stress in through-silicon-vias: Theory-of-elasticity approach

Simple physically meaningful analytical (mathematical) predictive stress models are developed for typical through-silicon-via (TSV) designs using theory-of-elasticity approach. Two extreme cases of the TSV geometry are addressed: disc-vias (with height-to-diameter ratios below 0.25), when plane stress approximation can be used, and rod-vias (with height-to-diameter ratios above 2.5), when plane strain approximation is applicable. The objectives of the analysis is to evaluate the effect of the size of the opening in the silicon material on the induced pressure at the boundary of the opening, when the TSV structure is heated up, and to assess the possible role of a “surrogate” layer, if any, on the level of the longitudinal interfacial shearing stresses. While the pressure at the Si opening and the maximum interfacial stresses determine the reliability of the silicon material, the longitudinal shearing stress at the Si-copper (Cu) interface is critical from the standpoint of the adhesive and cohesive strength of the TSV design. The numerical example is carried out for different opening radii and for the case when Indium is considered as a suitable buffering material. The calculated data indicate that larger openings in the Si result in lower pressures on it and in lower maximum interfacial stresses, especially if disc-like vias are employed. On the other hand, as has been shown earlier (see Suhir and Savastiuk, 2008) elastic stability of disc-vias should be evaluated and ensured. The developed models can be used also to determine if there is sufficient incentive for employing additional, “surrogate”, materials (i.e., materials not needed from the standpoint of the functional performance of the design) for lower thermally induced stresses.

A high intensity 200 mA proton source for the FRANZ-Project (Frankfurt-Neutron-Source at the Stern-Gerlach-Center)

At the University of Frankfurt a high current proton source has been developed and tested for the FRANZ-Project [U. Ratzinger, L. P. Chau, O. Meusel, A. Schempp, K. Volk, M. Heil, F. Käppeler, and R. Stieglitz, "Intense pulsed neutron source FRANZ in the 1-500 keV range," ICANS-XVIII Proceedings, Dongguan, April 2007, p. 210]. The ion source is a filament driven arc discharge ion source. The new design consists of a plasma generator, equipped with a filter magnet to produce nearly pure proton beams (92 %), and a compact triode extraction system. The beam current density has been enhanced up to 521 mA/cm(2). Using an emission opening radius of 4 mm, a proton beam current of 240 mA at 50 keV beam energy in continuous wave mode (cw) has been extracted. This paper will present the current status of the proton source including experimental results of detailed investigations of the beam composition in dependence of different plasma parameters. Both, cw and pulsed mode were studied. Furthermore, the performance of the ion source was studied with deuterium as working gas.

Evaluation of the pore size distribution of a forward osmosis membrane in three different ways

This paper adopted three different techniques to characterize the membrane widely used in the studies of forward osmosis. The first technique involved estimating the pore size distribution of the membrane by modeling the rejection of simple uncharged solutes in hydraulic pressure-driven experiments. The pore size distribution was determined through the relationship between solute rejection and the Stokes radius of the neutral solute molecules. In the second method, the transmission electron microscopy was used to characterize the membrane. This method enabled the direct observation of open pore radius and directly confirmed the presence of discrete active and real physical pores. The third technique used to determine pore size distribution is the Brunauer–Emmett–Teller nitrogen adsorption. The results indicate that the forward osmosis membrane shows a significant distribution of pore size. The pore radius distribution is approximately skewed positively, and the mean value is 0.25–0.30nm. This work also compared all the results, which show good agreement with the three techniques. Furthermore, the reflection coefficient is related to the pore size distribution obtained in this work, and the calculated values agree well with the experiment results.

Wave transformation by a dredge excavation pit for waves from shallow water to deep water

In this paper, an analytic study on wave scattering by a dredge excavation pit is conducted, where the pit is assumed to be axi-symmetric and idealized with its depth profile in radial distance being a simple power function. By using techniques of variable separation and series expansion, a series solution to the explicit modified mild-slope equation (EMMSE) is constructed and the convergence condition is clarified. It is clear that this analytic solution is valid in the whole wave spectrum from shallow-water waves to deep-water waves due to the use of the EMMSE, which is superior to previous long-wave analytic solutions. Based on this analytic solution, influences of the pit dimension including its depth, bottom radius and opening radius on relative wave amplitude (i.e., the wave amplitude relative to the incident amplitude) are investigated. It is shown that the pit size plays a more important role than the sidewall steepness does in affecting the wave pattern. With the broader validity than that of the long-wave model, it is found that the wave attenuation within and in the lee side of the pit intensifies first and then decreases as the incident waves becomes short.

Estimation of support pressure during tunnelling through squeezing grounds

High in situ stresses and poor quality of rock mass are primarily responsible for the squeezing behaviour of rock masses. This phenomenon is prevalent especially in the Himalayan region and hence rock engineers and engineering geologists have frequently encountered problems of stability during construction in this region. High in-situ stresses, poor rock mass quality, large overburden depth and large radius or span width of a tunnel or cavern in weak rocks are the factors which are responsible for the occurrence of squeezing ground condition. The present study involves development of a dimensionally correct empirical correlation for assessment of support pressure in tunnels which are excavated in squeezing ground condition. The correlation uses the concept of ‘joint factor’ as a measure of rock mass quality, allowable closure, depth and radius of opening as the governing parameters. Data from 52 different tunnel sections and one set of data from a mine gallery have been considered for analysis. The predicted results have been compared with the results obtained via existing approaches, based on rock mass quality (Q) and rock mass number (N). It was observed that the proposed correlation holds better with a correlation coefficient of 0.92 and estimated values of support pressure from the approach show better accordance with the observed values of support pressure as compared to other existing correlations based on Q and N values. The proposed correlation makes use of parameters which can be easily obtained at project sites. Therefore, it can become a handy tool for site engineers to predict the support pressure in squeezing ground conditions and take appropriate measures for the stability of underground excavations.

The effect of chain stiffness on moisture diffusion in polymer hydrogel by applying obstruction-scaling model

In order to understand the moisture diffusion, we combine the obstruction-scaling model with the moisture clustering in confined spaces of the polymer hydrogel, with relevance to the performance of the super desiccant polymer. Special attention is focused on elucidating the effect of chain stiffness by considering the conformation of polymer chain on the basis of polymer physics. Relevant parameters for calculations are determined from literature information as well as the best fits for reported data performed with the copolymer. Our results exhibit the moisture diffusion decreases with increasing chain stiffness represented by the persistence length. Note that the larger persistence length provides smaller radius of openings in void spaces, resulting in the stronger hindrance effect on the moisture diffusion. Higher temperature makes the water molecules to be easier to form clusters, which provides the decrease in diffusivity. The increase of moisture diffusion at low humidity is attributed to the swelling of the chain, whereas its decrease at high humidity results from the water clustering.

Active electron energy distribution function control in direct current discharge using an auxiliary electrode

The electron energy distribution functions are studied in the low voltage dc discharge with a constriction, which is a diaphragm with an opening. The dc discharge glows in helium and is sustained by the electron current emitted from a heated cathode. We performed kinetic simulations of dc discharge characteristics and electron energy distribution functions for different gas pressures (0.8 Torr-4 Torr) and discharge current of 0.1 A. The results of these simulations indicate the ability to control the shape of the electron energy distribution functions by variation of the diaphragm opening radius.

Design and Shielding Effectiveness of Electromagnetic Shielding Textiles

.In order to design better anti-radiation and electromagnetic shielding fabric and the clothing and makes it maintained better of electromagnetic shield effectiveness, the influence of radiation source, radiation distance, anti-electromagnetic radiation material, fabric structure, gap size, holes area, clothing exposed area as well as the tunnel effect and so on the fabric radiation protection performance were comprehensively discussed in this article. As well, according to these influence factor analysis the regular conditions that the electromagnetic shielding fabric and garment design should be meet. The analysis result indicated that the shielding effectiveness of the fabric was decreased with the increase of the radiant frequency, the fabric slit size, the hole area and enhanced with the growing of the metal content, the organizational structure close degree as well as the radiation distance.In the case of the equal shielding effect, the bigger exposed area leads weaker electromagnetic shielding effectiveness and if the exposed area oversize can cause the shield effect vanished. Also the clothing shield potency was related to the opening radius, the length, the inside and outside dielectric constant, the permeability of the shirt or cuff. The comprehensive effectiveness of electromagnetic shielding fabrics will be gradually improved if they can meet these regular conditions continually.

Intrafocal Pinning for Distal Radius Metaphyseal Fractures in Children

The purpose of this retrospective case control study was to evaluate the results of intrafocal pinning for distal radius metaphyseal fractures in children and to compare these results with conventional pinning. Data were collected from medical records and radiographs from patients who underwent closed reduction and percutaneous pinning for distal radius fracture in a Level I trauma center at the authors' institution between 2008 and 2010. Inclusion criteria included a dorsally angulated metaphyseal fracture without physeal involvement, an open distal radius physis, and a follow-up to radiographic union. A total of 10 patients with intrafocal pinning were compared to 26 patients with conventional pinning. Preoperatively, angulation was greater in patients who received intrafocal pinning than conventional pinning based on anteroposterior radiographs. Postoperatively, the 2 groups did not differ in angulation on either anteroposterior or lateral radiographs. One malunion and 2 pin-related complications occurred in the conventional pinning group, and 1 pin-related complication occurred in the intrafocal pinning group. The 2 groups did not differ by age, sex, side of injury, days to surgery, or initial shortening. This study affirms that the intrafocal pinning technique is an alternative to the conventional pinning technique for the stabilization of displaced metaphyseal distal radius fractures in children. Intrafocal pinning can also be used as a reduction tool for fractures that cannot be reduced by closed manipulation. The complications are comparable between the 2 techniques.

Bubble-Propelled Microjets: Model and Experiment

Using basic principles of diffusion and reaction, a one-dimensional mass transport model inside a catalytic microjet has been proposed. The effect of microjet geometry on mass transport has been investigated, and its effect on bubble growth and microjet motion has been predicted. Oxygen generation and its flux to one end of the microjet induce nucleation and growth of bubbles. The bubble growth and ejection/burst cause the microjet to move forward. Numerical investigations of the motion-related parameters, such as O2 flux, bubble generation rate and frequency, and average speed of the microjet motors during bubble growth, are found to depend closely on the length and opening radius of the microjet and concentration of H2O2 in the surrounding environment. The predicted results are compared to experimental data obtained from graphene oxide-based microjets, and they show good qualitative agreement. These results demonstrate that this simple model could be used to optimize catalytic microjet design.

Outcomes After Volar Plate Fixation of Low-grade Open and Closed Distal Radius Fractures Are Similar

Low-grade (Gustilo and Anderson Type I or II) open distal radius fractures (DRFs) have been treated by volar locking plate fixation. However, it is unclear whether the outcomes after volar locking plate fixation for low-grade open DRFs are comparable to those for closed DRFs. We asked whether low-grade open DRFs had worse DASH scores and higher infection rates than closed DRFs when the DRFs were treated by volar plate fixation. Twenty consecutive patients treated by volar locking plate fixation for low-grade open DRFs constituted the open fracture group, and 40 patients were selected from among the total number of patients treated by volar, locking plate fixation for closed DRFs as the closed fracture group. Complications including infection were recorded. Clinical outcomes and radiographic assessments were performed postoperatively at 3 months and 1 year. At 3 postoperative months, wrist flexion and extension, grip strengths, and DASH scores were better in the closed fracture group; however, no difference was observed postoperatively between the two groups in terms of any functional outcome measure at 1 year. Any of the radiographic parameters were not different between the groups. There were no differences in infection rate and in any other complication rate between the groups. Although functional outcomes of open DRFs were inferior to those of closed DRFs at 3 months, at 1 year, outcomes of low-grade open DRFs were found to be comparable to those of closed DRFs when volar plate fixation was used.

High Intensity Focused Ultrasound Optimal Device Design for Targeted Prostate Cancer Treatment: A Numerical Study

A parametric study was performed to design a device capable of treating small targeted regions within the prostate using high intensity focused ultrasound, while sparing the surrounding organs and minimizing the number of elements. The optimal focal length (L), operating frequency (f), element size (a) and central opening radius for lodging an imaging probe (r) of a device that would safely treat tissue within the prostate were obtained. Images from the Visible Human Project were used to determine simulated organ sizes and treatment locations. Elliptical tumors were placed throughout the simulated prostate and their lateral and axial limits were selected as test locations. Using graphics processors, the acoustic field and Bio-Heat Transfer Equation were solved to calculate the heating produced during a simulated treatment. L, f, a and r were varied from 45 to 75 mm, 2.25 to 3 MHz, 1.5 to 8 times the wavelength and 9 to 12.5 mm, respectively. The resulting optimal device was a 761-element concentric-ring transducer with L = 68 mm, f = 2.75 MHz, a = 2.05λ and r = 9 mm. Simulated thermal lesions showed that it was possible to treat target tumors consistent with reported locations and sizes for prostate cancer.

Studies on In-Plane Stability Behavior of Arches with Web Openings

As a new type structural member, the steel arch with web openings combines the features of both arches and members with web openings and its applications has been found. Studies on in-plane stability behavior of two-hinged arches with web hexagonal openings are made using Eigen buckling model of the finite element software ANSYS. The buckling load and buckling mode are obtained and the in-plane buckling mode is antisymmetrical. It is shown that buckling load decreases gradually as the circumcircle radius of openings increases and it increases as the gap between openings increases through analysis of buckling load with different parameters such as r/h, g/h, f/l. It can be found that the structural efficiency is the highest when the radius of openings is 0.3h with the aid of optimized function.

Design Method about Spherical Diaphragm Sealing of Tube Channel in High Pressure Heat Exchanger

Spherical diaphragm seal dish of tube channel open end in high pressure heat exchanger is a new engineering structure that used in petrochemical hydrogenation unit, and its design technology is not reported now. It is inconvenience to analyze each case by limited element method. Design method of formulas is proposed to calculate both radial offset displacement and its thickness of spherical diaphragm based on shell elasticity mechanics. Relation formulas are deduced about arch height, open end radius, offset displacement by geometry. Two presuppositions are deduced for spherical diaphragm successful to run according to technology theory and function analysis of seal dish structure, which can be used for engineering design.

Finite-element simulation of a beam-to-column connection with circle web opening

Connections with pre-cast hollow sections are commonly preferred in recent times because of the convenience they offer. The present work describes a finite-element model developed to simulate the structural behaviour of beam-to-column joints with hollow sections. In order to verify the model, a simple beam-to-column joint is modelled in a laboratory test; the joint consists of an end-plate welded to a beam and bolted to a column. The validity of the finite-element model is then established by comparing its results with the corresponding experimental tests. Thereafter a parametric study is carried out to investigate the structural behaviour with variations in the pre-cast web opening radius and distance from the connection.