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Magnetic resonance coupling wireless power transmission (WPT) provides a safe and efficient power supply for small household appliances and implanted devices, but the tolerance of the transmission distance is poor. To improve the robustness of the transmission distance of the magnetic resonance WPT system, a method of using a reconfigurable helical coil array is proposed. Compared with the traditional four-coil structure of the same volume, different source and load coils are selected under distinct distance conditions. The coupling coefficient between the coils is changed to increase the stability of transmission efficiency and distance. To avoid the mechanical movement, all source and load coils have been adjusted at fixed position. Moreover, a control method is introduced to achieve coil switching. The experimental results show that the transmission distance of the proposed system is increased to 1.75 times of the coil diameter, while the efficiency remains above 70%.

Air conditioners (AC) and water heaters have become common needs in households and the hotel industry. This shows that the need for electric power is increasing. To reduce electricity consumption which is high enough. Engineering technology needs to be done for air conditioning as well as water heating. This engineering is called ACWH (Air Conditioner Water Heater). The way the ACWH system works is to utilize the wasted heat from the AC system to heat water with the addition of a fin heat exchanger, where the heat exchanger is designed to utilize the energy already in the system. This study used experimental research methods by testing at temperatures of 16, 18 ?, and 20 ? AC. The test results showed that the finned shell helical coil type heat exchanger was able to produce a water temperature of 55 ? in the test with an AC temperature of 18 ?.

The present paper investigates the performance of helical coil solar cavity receiver based parabolic trough concentrator (PTC) for the conversion of energy received from the Sun into useful heat and finally electricity. The experimental set-up has been designed in such a way that it enhances heat transfer coefficient and reduces losses in the PTC. The PTC comprised of a blackened helical coil made up of two concentric borosilicate glass cylinder with vacuum in the annulus, which is kept at a focal line of PTC. The vacuum significantly reduces the losses which are evident from a relatively higher temperature of a 565 K obtained at the surface of the helical coil. Heat loss from helical coil solar cavity receiver has also been investigated and it was found that with the increase in vacuum pressure at annulus by 50%, the losses from the receiver has been increased by 26.67%. The heat loss from receiver has been observed to be proportional to the vacuum pressure within the annulus space.

The behavior of two-phase flow and corresponding flow regimes in helical tubes significantly differ when compared to two-phase flows in straight tubes due to centrifugal and torsion effects. In order to gain physical insight and gather data for validating computational models, a large number of experiments were performed on a helical coil experimental setup operated with a mixture of water and air. The experimental data were used to assess the predictive capabilities of current two-phase Computational Fluid Dynamics (CFD) models based on the Volume of Fluid (VOF) approach. In the present paper, a comparison of the CFD simulation results with the high-resolution experimental data is discussed, with special emphasis on two-phase pressure drops and void fraction distributions. It is shown that the CFD VOF model is able to correctly capture the occurrence of five flow regimes observed in the experiments, namely bubbly flow, plug flow, slug flow, slug-annular flow, and annular flow. However, a good quantitative agreement for pressure drops and void fraction distributions is found in slug flow and slug-annular flow regimes only. The good agreement found only in a limited range of flow regimes demonstrates that there is not a single set of best-practice guidelines for CFD VOF models that can be applied across a wide range of two-phase flow regimes. Also, there is not a single mesh that can be used to simulate all of the flow regimes and a case-specific mesh and time-step convergence study is needed for each individual flow regime. In the current study, optimal mesh size and time step were obtained for a slug flow test case. Hence, good agreement was obtained only for similar flow regimes, leading to significant disagreement with experimental data for test cases with substantially different flow patterns.

In the present study, deep learning neural network model has been employed in many engineering problems including heat transfer prediction. The main consideration of this document is to predict the performance of the boiling heat transfer in helical coils under terrestrial gravity conditions and compare with actual experimental data. Total of 877 data sample has been used in the present neural model. Artificial new Neural Network (ANN) model developed in Python environment with Multi-layer Perceptron (MLP) using four parameters (helical coils dimensions, mass flow rate, heating power, inlet temperature) and one parameter (outlet temperature) has been used in the input layer and output layer in order. Levenberg-Marquardt (LM) algorithm using L2 Regularization to find out the optimal model. A typical feed-forward neural network model composed of three layers, with 30 numbers of neurons in each hidden layer, has been found as optimal based on statistical error analysis. The 4-30-30-1 neural model predicts the characteristics of the helical coil with the accuracy of 98.16 percent in the training stage and 96.68 percent in the testing stage. The result indicated that the proposed ANN model successfully predicts the heat transfer performance in helical coils and can be applied for others operation concerned with heat transfer prediction for future works

The parabolic troughs are the most popular line focusing collectors. They are being used for process heating and medium temperature applications since long. In these collectors, the sunlight is concentrated at the receiver fixed at the focal line of the parabola. In general, the tubular types of receivers are used in the line focusing collectors. The working liquid is allowed to flow through the receiver tube. In the current study, the performance of a parabolic trough collector with the modified receivers is analyzed by experiments. Two types of receivers, viz. ‘U’-tube receiver and ‘helical coil receiver,’ enclosed in an evacuated glass tube are used. The system is installed at Nagpur [21.14° N, 79.08° E]; experiments have been performed in the month of February. The highest output temperature of 90 °C and the corresponding efficiency of 90.92% is obtained with helical coil receiver geometry. The details of receiver geometries and the experiments are discussed in this article.

This paper presents a highly efficient power transfer system based on a co-design of a class-E power amplifier (PA) and a pair of inductively coupled Helical coils for through-metal-wall power transfer. Power is transferred wirelessly through a 3.1-mm thick aluminum barrier without any physical penetration and contact. Measurement results show that the class-E PA achieves a peak power gain of 25.2 dB and a maximum collector efficiency of 57.3%, all at 200 Hz. The proposed system obtains a maximum power transfer efficiency of 9% and it can deliver 5 W power to the receiver side through the aluminum barrier.

The present study applied computational fluid dynamics (CFD) to investigate the heat transfer of Newtonian (water) and non-Newtonian (0.3 %wt. aqueous solution of carboxymethylcellulose (CMC)) fluids in the presence of Al2O3 nanoparticles. To analyze the heat transfer rate, investigations were performed in a vertical helical coil as essential heat transfer equipment, at different inlet Reynolds numbers. To verify the accuracy of the simulation model, experimental data reported in the literature were employed. Comparisons showed the validity of simulation results. From the results, compared to the aqueous solution of CMC, water had a higher Nusselt number. In addition, it was observed that adding nanoparticles to a base fluid presented different results in which water/Al2O3 nanofluid with nanoparticles’ volume fraction of 5 % was more effective than the same base fluid with a volume fraction of 10 %. In lower ranges of Reynolds number, adding nanoparticles was more effective. For CMC solution (10 %), increasing concentration of nanoparticles caused an increase in the apparent viscosity. Consequently, the Nusselt number was reduced. The findings reveal the important role of fluid type and nanoparticle concentration in the design and development of heat transfer equipment.

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The design, simulation, and development of a sequentially-fired pulse forming network (SFPFN) to power a large bore helical coil electromagnetic launcher (HCEL) is presented and discussed in this thesis. This investigation furthers the previous work of a medium-bore HCEL SFPFN. Improvements on the previous design include increasing total stored energy and peak current. Additional improvements include a more robust charging program as well as a computer controlled firing system. The new field programmable gate array (FPGA) firing system allows for an easily variable and accurate firing system as well as fault monitoring trip out system to protect the SFPFN in case of a fault.

By directing the laser-driven electromagnetic pulses along a helical path, one can achieve a travelling-field accelerator arrangement for simultaneous beam shaping and re-acceleration of laser-accelerated protons. The dynamics of guided acceleration of the transiting protons was studied by varying the length of the helical coil. Experimental data shows that the protons co-moving with the field region exhibit stronger focussing while increasing the coil length, with an increase of kinetic energy due to simultaneous post-acceleration. The net energy gain for a coil of constant pitch however saturates eventually when the post-accelerated protons overtakes the accelerating field region in due course. 3D particle tracing simulation underpins the dynamics of beam transport inside the coil, which highlights the requirement for a variable pitch coil geometry in order to sustain the post-acceleration over an extended coil.

Background In endovascular embolisation for an intracranial aneurysm, after framing coil deployment, soft coils (often called filling coils) are usually selected to fill inside the cage of previous coils. Various kinds of filling coils are available, although each coil has its own characteristics. Understanding their differences to ensure proper coil selection is important to achieve successful embolisation. The purpose of this study was to investigate the characteristics of various filling coils. Materials and methods The authors developed a radiolucent coil to evaluate the performance of coils under conditions simulating the course of embolisation. Experimental embolisation was performed by using a silicone aneurysm filled with radiolucent coils. Indices including area, circularity, centroid position and coefficient of variation were investigated by analysing the figures of the filling coils after being inserted into the radiolucent coil under fluoroscopy. Results The characteristics of each coil depended on the coil design. The helical coil had the highest circularity and centroid position scores and lowest area score. Therefore, it tended to develop a compacted mass. The low shape-memory coil had the lowest circularity, second-highest centroid position and highest coefficient of variation scores. Therefore, it tended to develop irregularly shaped distribution with low reproducibility. Complex coils generally had higher area and circularity scores. Therefore, they tended to provide a balanced distribution with relatively expanded mass and less small compartmentation. Conclusions The evaluated characteristics of various filling coils should be useful for appropriate selection of filling coils.

Building Construction Involves Use Of Stirrups To Give Strength To Columns And Beams And Are Widely Used In Various Shapes In Steel Reinforcement. It Is Regular Practice To Make Stirrups On Construction Sites. Existing Engineering Standards Recommend Use Of Continuous Helical Coil For Better Strength Of Structure But It Is Having A Very Rudimentary Level Of Technology. Hence This Work Focuses On Developing A Coiling Machine As An Integrated System Of The Rolling Mill Where The Steel Bars Are Produced. The Integrated Coiling Machine Will Overcome Almost All Problems And Limitations Associated With Manual Stirrup Making And Even Of Semiautomatic And Full Automatic Stirrup Making Machines. This Paper Embarks On Integration Of Stirrup Making Activity With Rolling Mill So As To Take The Advantages Of Plastic Deformation Of Steel At Elevated Temperature, Imbibing The Metallurgical And Mechanical Properties And Eliminating Residual Stresses Compared To Todays Stirrup Making Practices.

The objective of the present work is to study the influence of curvature and Reynolds number on local heat transfer coefficient in a helical coil with water as the working medium. The local wall temperature is measured not only in the axial direction (along the length of coil) but also in the circumferential direction using infrared thermal imaging technique. The test sections are made of thin walled stainless steel (SS 304) tubes having an inner diameter varying from 5.4 to 7.5 mm with a thickness of 0.2 and 0.25 mm. The coil diameter to the tube diameter ratio ranges from 13.1 to 67 and coil pitch is 50 mm. The experimental results of friction factor and overall averaged total Nusselt number are compared with the available correlations in the literature. Correlations are suggested for overall averaged and local circumferentially averaged Nusselt number for inner side, outer side and total surface (inner side and outer side) of a helical coil. (C) 2015 Elsevier Ltd. All rights reserved.

The helical-coil once-through steam generator (OTSG) is usually used in the nuclear power plant when the compactness of equipment was taken into consideration. The investigation of flow parameters in the primary side is valuable for the optimization of the OTSG. The purpose of this research is to obtain a further understanding of fluid behaviors in the primary side of the OTSG to achieve a more rational design. Using ANSYS ICEM and ANSYS FLUENT, a three-dimensional (3D) computational fluid dynamics (CFD) model was created and analyzed. Through a series of cases, the velocity profiles and pressure drop through the primary side of the helical-coil OTSG have been calculated, and the influences of different structure designs on the coolant flow parameters have also been tested. Ultimately some pertinent suggestions for improvements were proposed, and insight is obtained into the importance of various modeling considerations in such a model with a complicated structure and large-scale grids.

The study represents a new approach to design helical coil spring by using workbench. Response surface modeling and analysis of helical spring by considering longitudinal and translational invariance have been carried out. The considered design parameters are coil diameter, wire diameter, height, number of turns elastic modulus in X and Y direction, force. Simple equation is proposed which gives the values of compressive stress of helical coil spring by carrying out regression analysis. It is observed that force and material property are significant parameters which affect compressive strength. The relationship between design parameters and compressive strength has been obtained.

Helical coil electromagnetic launchers (HEML) using rail-fed strategy, local excitation and single-turn commutation, solve the problem of synchronization control perfectly. Through the simulation a novel helical coil launcher has been designed adopting the basic HEML's structure. A D-shaped cross-section armature has been proposed in order to achieve the maximum projectile velocity. The energizing length of the driving coil as well as the armature position of the maximum force has been determined. The maximum driving force on the armature increases with the increasing coil axial length, and the armature acceleration reaches its maximum value when the ratio of axial to radial length of the coil is 1∶2. The force distribution of the armature and driving coils has been analyzed. Theoretical analysis and experiments show that the reluctance armature can obtain larger thrust under low current condition, but the coil armature is better in the case of high current while the ferromagnetic material is saturated.

The guidewire is a small diameter, steerable wire which facilitates the navigation of the interventional devices such as stent, balloon, or coil in endovascular intervention. The guidewire has an elongated flexible body and a relatively more flexible ribbon tip. The elongated body (shaft) is tapered to the ribbon tip. The composition of the helical coil formed ribbon tip is different than the elongated body. In this article we demonstrate the correlation between the material composition and the kinking resistance of guidewire. The identified metal composition of the core wire was 18-8 stainless steel and the helical coil composed of platinum-nickel alloy and the material of tip bond was tin. The kink angle which caused permanent deformation were significantly higher on the helical coil (=68,3o) due to the higher flexibility of the helical coil than that was found on the shaft portion (=55o) (p=0,00032). The remnant angel induced by 90o kinking on the helical coil was significantly lower (=15o) than that was observed on the shaft portion (=23,9o) (p=0,00046). The deformation of the helical coil was smaller due to the higher flexible properties of the platinum-nickel alloy material against the stainless steel.

A key challenge for future switching technologies, especially in the context of the substitution of the strong greenhouse gas sulphur hexafluoride and the ongoing development of DC grids, is the increase of the contact opening velocity within switching devices. Thus, in this contribution a compact helical coil operating mechanism is developed and first experimental investigations are performed to characterize the accelerating and breaking performance of the mechanism. The helical coil arrangement is supplied by currents up to values of several kilo-amperes and the movement of the mechanism is analyzed.

The endovascular coiling of very small ruptured aneurysms with difficult geometry presents a significant treatment challenge because of potential dangerous complications, such as intraprocedural ruptures. We report our initial experience with the use of a dual microcatheter technique, combined with new hypersoft helical coils, for the treatment of these difficult lesions. Fourteen very small aneurysms with a maximum diameter of ≤3 mm that presented difficult configurations, such as a wide neck or an important branch vessel arising from the fundus, were identified using digital subtraction angiography. These lesions were successfully treated using a dual microcatheter technique and new hypersoft helical coils. There were no intraprocedural ruptures or procedure-related thromboembolisms. Complete or near-complete occlusions were achieved in all of the lesions. A Raymond score of RS 1 was achieved in eight of the aneurysms (57.1%) and an RS 2 was achieved in six of the aneurysms (42.9%). The mean packing density was 35.5%. At the last post-procedure clinical follow-up, a good clinical outcome (a modified Rankin scale score of 0–2) was observed in 11 of the patients (91.7%). The result of angiographic follow up in 11 cases showed two recanalized aneurysms. The use of the dual microcatheter technique and new hypersoft helical coil allowed for stable coil framing and good packing in geometrically difficult tiny aneurysms and presented a low rate of adverse events related to the procedure. The technique provided an efficient strategy for treating very small aneurysms with difficult configurations and high risks.

A molten salt helical coil steam generator is an alternative to kettle- or drum-type evaporators which are currently used in commercial-scale solar thermal power plants. A 300 kW prototype was tested during the OPTS project at ENEA. The experimental results presented in this paper have been used to validate a detailed heat transfer analysis of the whole system. The heat transfer analysis deals with the study of both the overall heat transfer coefficient and the shell-side heat transfer coefficient. Due to the specific features of this type of system, no correlations were available in the literature. A new numerical model to predict the performance of large-scale systems is also presented. © 2016 Author(s).

Ege, Yavuz (Balikesir Author), In this paper, a new helical coil electromagnetic launcher is designed, which launches a magnet projectile without using any mechanical launching equipment, but by applying momentary varying current to the helical coil. For measuring the velocity of the magnet projectile in different stages, a LabVIEW-based software and hardware system is developed, and it is also used for improving the performance of the output velocity of the magnet projectile by changing the ignition time of the coils. This paper distinguished the new accelerator coil design and the software, which uses LabVIEW for the first time in this area. With the LabVIEW-based software, optical sensor data are acquired and processed, and ignition triggering control is carried out. Ignition timings on sequential four helical coils are optimized to produce the maximum acceleration in each coil, and thus the maximum velocity of the magnet projectile at output. An NI Data Acquisition 6010 data acquisition card is used for communication and gathering information throughout the entire launching process. In addition, the effects of changing the current magnitude, ignition time, magnet projectile length, and diameter to the output velocity of magnet projectile are investigated and discussed in detail.

For next high temperature reactor projects, e.g. for electricity production or nuclear process heat applications, the steam generator is a crucial component. The typical design consists of a helical coil tube bundle steam generator with several tubes in different tube cylinders connected in parallel. This type of steam generator was a significant component used in the THTR-300. The influence of different heat transfer correlations for the primary side on the steam outlet temperature is being analyzed by the nodal thermal hydraulics code TRACE for the THTR-300 steam generator and compared to experimental data. The results of the standard TRACE code are compared to results with modified Nusselt numbers for the primary side and they will be elaborated in this paper. These modified Nusselt numbers were used for the heat transfer calculations of the THTR-300 steam generator design.

In this paper, analytical calculations using a novel mutual inductance formula for a resonant wireless power transmission system using helical coils. The look-up table of critical variables during the mutual inductance calculation process was formulated. The calculation results for resonant frequency and insertion loss were compared with experimental results when the distance between the two helical coils in a structure where the transmission and reception is symmetrical was varied with 10 mm increments from 53 mm to 500 mm. On average, the resonant frequency showed a difference of 5.63 % between the experimental results and the calculation results. The insertion loss had an average difference 2.25 dB where the smallest difference of 0.33 dB occurred with 290 mm. It was found that the experimental results without using a balun were in greater agreement with the calculation results.

Michael Faraday (1791–1867) was born in Newington Butts, which is now part of London. He had little formal education beyond day school as a young boy. Yet from a position as apprentice to a bookbinder at the age of 14, Faraday would become the Superintendent and Director of the laboratory at the Royal Institution, where his careful experimental work on electro-magnetism laid the foundation for Maxwell’s electromagnetic theory of light. Faraday’s most significant discovery, and the topic of the reading selection below, was presented initially in his address to the Royal Society on November 24, 1831. Herein, he describes his attempts to obtain “electricity from ordinary magnetism.” The lecture begins with a brief reminder of how bodies held in electrical “tension”—we would say they have an electrical potential, or voltage, difference—induce an electrical polarization in nearby materials. Before proceeding, he explains how his work was inspired, at least in part, by Arago’s recently observed magnetic phenomena and by Ampere’s “beautiful theory” of magnets.

Double wall helical coil heat exchangers are widely used in a variety of applications. These heat exchangers are used anywhere that requires an added layer of protection from cross-fluid contamination such as in indirect water heaters. Here, the coil is heating a potable water tank with coil water which is often infused with a glycol mixture. Since contamination of the potable water would be detrimental to human health, the added protection of a double wall coil is necessary. Unfortunately, the double wall coil is inherently difficult to design due to unknown intertubular contact. This intertubular contact is hidden in nature and difficult to evaluate by nondestructive means. This paper uses STAR-CCM+ to create a computational fluid dynamic model of the double wall helical coil in respect to GAMA indirect water heater continuous draw test conditions. Using CFD, the model is validated with single wall helical coil Nusselt number correlations determined from experimentation. Then, a parametric study is performed to determine what parameters of the coil can be changed to effectively overcome the intertubular thermal loss. From this study, it is found that tube length has a linear positive relationship with coil output density and can be used to calculate necessary lengths for a desired output. Also, it was found that the experimental Nusselt number correlations identify with the results calculated by the double wall CFD model when intertubular contact percentage is used as a correction factor.

In this paper, an efficiency improvement method in the wireless power transfer system based on magnetic resonance is proposed. A combined helical-spiral structure is adopted for self-resonant coil and source and device coils are designed using circular loop structure. The proposed resonator utilizing combined helical-spiral structure yields 13 % efficiency improvement over that of an existing helical type resonator when the transmitting and receiving coils are separated by 120 mm. In addition, the size can be reduced by 33 % comparing to the previous resonator.

As an application of two-way shape memory effect (TWSME), NiTi shape memory alloy (SMA) helical coils were incorporated into a cold weather jacket for intelligent insulation that senses and reacts to environmental conditions. The coils were annealed and thermo-mechanically trained such that the pitch of the coil is 10 mm or 15 mm under cold conditions and the coil is flat in warm conditions. The effects of the TWSMA coils on insulation and temperature buffering properties of the clothing system were evaluated under transient temperatures (30 °C, 55% relative humidity to 0 and −5 °C, 19% relative humidity) using a human-clothing-environment simulator. The flat coils at 30 °C were expanded at both 0 and −5 °C spontaneously, creating an adequate air layer between the adjacent layers of the clothing system. Consequently, the microclimate temperatures were raised and buffering effects upon a sudden drop of environmental temperature as well as thermal insulation were improved. The insulation effects increased as the pitch of the coil increased. The wearers reported a warmer feeling with the TWSME coil attached clothing system. However, the reported thermal feeling ratings did not show statistically significant differences except at the moment of the transition point. The results point toward the possible application of TWSME using SMAs in the development of intelligent garments and provide useful insights into the further studies for practical use.

Aims Soft and small coils are known to be appropriate for the treatment of small aneurysms. The purpose of this study was to determine whether the new HyperSoft® helical coil, which is softer and smaller than its predecessors, has any effect on the packing performance in a matched-pair study with an old HyperSoft® helical coil. Materials and methods Thirty-six consecutive patients harboring 43 cerebral aneurysms treated with new HyperSofts were included in this study. Forty-one aneurysms treated with old HyperSofts were identified from our database as matched controls based on similar volumes and locations. Packing attenuation, adverse events during the procedures, and angiographic occlusions were observed and compared between the two groups. Results The mean packing density was significantly higher in the new HyperSoft® group compared to the control group (35.5% vs. 26.9%), and a larger proportion of the aneurysms embolized with the 1.5 mm size coil, which has higher packing density. There was no difference in immediate and midterm angiographic outcomes. There was no difference in the rate of intraprocedural perforation, but there was no intraprocedural rupture related to the 1.5 mm coil. Conclusions The use of new HyperSoft® helical coils allows higher packing density comparable with the old technology. New HyperSoft® coils, especially those with 1.5 mm loop diameter, can be expected to fill smaller residual spaces in small aneurysms and may be helpful in preventing recanalization.

This paper describes the application of the coupled FE-BEM (finite element-boundary element method) for the numerical harmonic analysis of the linear dynamic behavior of a magnetostrictive Terfenol-D rod in water. The magnetostric- tive rod is three-dimensionally modeled to transduce applied electric current in a helical coil around the rod to mechanical displacement. The steady-state resonance response of the displacement is shown.

In the steam generator of the fast breeder prototype reactor "Monju", heat exchange tubes of helical coil type are utilized. Steam-water two-phase flows in the helical coil tube have unique characteristic due to effects of centrifugal acceleration. In this paper, we visualized gas-liquid two-phase flows in each the helical coil tubes with two curvature radii to investigate the effect of centrifugal acceleration, and also the slug flow in parallel helical coil tubes with same pressure condition at outlet part are visualized.

In the steam generator of the fast breeder prototype reactor “Monju”, heat exchange tubes of helical coil type are utilized. Steam-water two-phase flows in the helical coil tube have unique characteristic due to effects of centrifugal acceleration. In this report, we visualized gas-liquid two-phase flows in the helical coil tube for providing the flow pattern map, and suggested the method for reconstructing the interfacial structures of gas-liquid two-phase flows in the cross-section of the tube. The method was applied to artificial images and experimental images, and the applicability was discussed.

Publisher Summary Advanced solid modeling tools make up curved design. While these tools are not necessarily more difficult to master, they do open up a new range of modeling possibilities, including some rather complex 3D designs. This chapter introduces revolve, shell, taper, loft, path extrusion, and sweep. Revolve easily creates complex revolved shapes based on the concept of solid or surface of revolution, and this command has no other equivalent in AutoCAD. Shell is one of several AutoCAD 3D commands “borrowed” from engineering solid modeling software due to their usefulness. The command creates a “shell” of a predetermined thickness out of a solid object. Loft is a recent addition to the AutoCAD toolbox, added along with many other 3D enhancements in AutoCAD 2007. Path extrusion and sweep, which follow next, are commands with a similar mission but different approaches. Path extrusion is the older command and still quite useful in certain situations, while the newer sweep just expands and simplifies the same idea.

A CFD code, MSG (Multi-dimensional Thermal-hydraulics Analysis code for Steam Generators), which is optimized for the helical coil type steam generators of the MONJU Fast Breeder Reactor at Tsuruga, Japan, has been developed. The purpose of this study is to validate the MSG code against experimental data recorded at MONJU and at the 50 MW steam generator test facility (SGTF) at O-arai Engineering Center, Japan, and to perform a cross-correlation with results from the superCOPD code. Quantitative all benchmarks produced sodium temperatures within 2% of measured values, whereas steam temperatures were scattered within 5%. Qualitative, discrepancies between the calculational mesh and the actual physical model of the facilities resulted in higher deviations in a fine mesh than in a crude and in the MONJU benchmarks notable surges were observed in the outlet steam and sodium temperatures. The SGTF in-vessel sodium temperature distributions revealed an overestimated rate of heat transfer. Finally, in the superC...

The Large Helical Device (LHD) is a plasma physics experimental device with a magnetic stored energy of 960 MJ, consisting of two superconducting (SC) helical coils and six SC poloidal coils. The trial operation and the first plasma discharge of the Phase I project for LHD were completed on 31 March 1998 as initially planned. The second experimental campaign was conducted with additional heating using two NBI devices. The third campaign started in June 1999 and was completed in January 2000. Many plasma heating tests with a plasma field of up to 2.90 T were carried out. Major test results on the SC magnet system for LHD are as follows: (1) The LHD cryogenic system was successfully operated for 13 400 h and proved its high reliability. (2) A central field of 2.91 T at a radius of 3.60 m was achieved at an inner helical coil current of 11.08 kA, a middle helical coil current of 11.83 kA and an outer helical coil current of 12.02 kA. (3) All six poloidal coils were excited stably. (4) Nine flexible SC bus lines with a total length of 497 m were operated stably and safely.

Clinical experience suggests that overlapping coronary stents result in an increased in-stent restenosis. This study investigates the underlying mechanisms in a porcine coronary model. Single or two overlapping self-made stainless steel single wire sinusoidal helical coil stents were randomly deployed in the right coronary artery of 20 cross-bred pigs. The pigs underwent a control angiogram at 6 weeks and were then sacrificed. Quantitative coronary analysis before, immediately after stent implantation, and at 6 weeks was performed using the semiautomated Polytron 1000 system. Morphometry was performed using a computerized morphometric program. Angiographic analysis revealed a decreased recoil in the overlapping group (1% vs 4%: P < 0.02) and a significantly larger minimal stent lumen diameter at follow-up in the single stent group (2.87 ± 0.16 vs 2.58 ± 0.22 mm, P = 0.005). Histopathology showed a significantly increased injury (1.27 ± 0.43 vs 0.83 ± 0.44, P = 0.042) and inflammatory reaction (1.51 ± 0.11 vs 1.09 ± 0.54, P = 0.035) surrounding the stent filaments in the overlapping stent group. Morphometric analysis showed a significantly higher neointimal hyperplasia (3.34 ± 0.68 vs 2.16 ± 1.48 mm2, P = 0.034) in the overlapping stent group. Overlapping stents result in a more pronounced coronary vessel injury resulting in more inflammation and neointimal hyperplasia compared to single stents.

Although biocompatibility of biodegradable stents is controversial, stents made of high molecular weight poly-l-lactic acid (PLLA) are thought to be the most promising. We investigated the biocompatibility of PLLA stents histologically and angiographically in porcine coronary arteries. The Igaki-Tamai stent is made of PLLA monofilaments (molecular mass 183 kD) with a zigzag helical coil design. Fourteen PLLA stents in 6 pigs and 9 Palmaz-Schatz half stents in 9 pigs were implanted in 15 normocholesterolemic pigs. Stents were mounted on a delivery catheter, and were implanted percutaneously into coronary arteries. Coronary angiography was performed before and immediately after stenting, at 2 and 6 weeks in five PLLA pigs and nine Palmaz-Schatz pigs. Histological studies were performed in PLLA pigs: 2 pigs at 2 weeks, 3 pigs at 6 weeks, and 1 pig at 16 weeks with hematoxylin-eosin and elastica van Giesons stains. All PLLA stents were successfully delivered. No stent thrombosis was detected in either group. There were no significant differences in minimal lumen diameter (MLD) or percent diameter stenosis between the PLLA and Palmaz-Schatz stent groups immediately after implantation, or at 2 or 6 weeks after implantation. Histological studies at 2, 6, and 16 weeks revealed no inflammation and minimal neointimal coverage on the PLLA stent struts. The PLLA stent maintained its structure for up to 16 weeks. These results suggest sufficient biocompatibility and strength of PLLA biodegradable stents in porcine coronary arteries. Clinical trial is now underway to validate the safety and usefulness of PLLA stents in humans.

This study presents a theoretical model of the general stress state found in helical implantable leads in bending. The model accurately predicts stress in large filarity coils made from clad wire. The stress is predicted using flexural rigidity of the coil and is developed to include the effects of coil pitch and the relative amounts and composition of the coil materials. The results is verified using finite element models of coils made from MP35N wire and MP35N clad silver wire. The resulting model will be especially useful for the fatigue analysis and engineering design of implantable leads which are built in this manner.