SGEMP Response of Large, Multiwire Satellite Cables

Compressive behaviours of novel SCS sandwich composite walls with normal weight concrete

We present the design and the performance evaluation of a new interconnect for large-scale densely packed electronically scanned antenna arrays that utilize a high-speed digital board-to-board vertical connector. The application targets microwave tissue, imaging in the frequency range from 3 GHz to 8 GHz. The tissue-imaging arrays consist of hundreds of active antenna elements, which require low-reflection, low-loss, and low-crosstalk connections to their respective receiving and transmitting circuits. The small antenna size and the high array density preclude the use of coaxial connectors, which are also expensive and mechanically unreliable. Modern board-to-board high-speed connectors promise bandwidths as high as 12 GHz, along with high pin density, mechanical robustness, and low cost. However, their compatibility with the various transmission lines leading to/from the miniature printed antenna elements and microwave circuitry is not well studied. Here, we focus on the design of the transitions from coplanar waveguide transmission lines to/from a high-speed vertical connector. The performance of the interconnect is examined through electromagnetic simulations and measurements. Comparison is carried out with the expensive sub-miniature push-on sub-micro coaxial connectors commonly used in miniature radio-frequency electronics. The results demonstrate that high-speed vertical connectors can provide comparable performance in the UWB frequency range.

Footprint scaling may reduce wire lengths when more metal layers are available for routing. To achieve optimal wire length, footprint should be very small in which case pin density will be extremely high. However, high pin density may lead to detailed routing failure. We demonstrate that there is a threshold pin density beyond which standard routing heuristics fail to access pins on the bottom layer, even with unlimited number of metal layers available for routing. Future technologies, such as vertical slit field-effect transistor (VeSFET), may have layouts with pin density exceeding the threshold. We show that VeSFET layouts are still routable within footprint using two-sided routing. Compared to one-sided routing, two-sided routing achieves shorter wire lengths and fewer vias, hence lower interconnect capacitance and better performance.

A study has been completed which compares four types of permanent electrical connections (soldered, solderless wrapped, percussive welded, and resistance welded) under environmental conditions of vibration, shock, temperature extremes, corrosion, humidity, and bending. Only good-quality connections were included in this study, and they represented the current state-of-the-art for each type. Under these conditions the connections showed no significant degradation in their electrical characteristics as long as they remained mechanically secure. Differences in the four types of connections were therefore assessed in relation to their mechanical characteristics. Consequently, one of the more important results of the study was the recognition of fatigue life as the most important mechanical connection characteristic when comparing connections which meet the high standards of the Bell System for electrical stability. Using fatigue life as a basis for comparison and soldered connections as a reference standard, the major conclusions with regard to general wiring (the connection of wires to terminals, such as surface and local cable wiring) are as follows for the conditions that existed in this study: (a) monitored percussive welded connections are superior to soldered connections; (b) over-all, solderless wrapped connections are essentially equivalent to soldered connections; (c) resistance welded connections are significantly inferior to soldered connections. Although differences were found among the types of connections, no evidence was obtained that any of the connection types are not satisfactory as presently used in normal Bell System applications.

The global pinning force density is calculated for a superconductor containing dense and strong pins using a statistical method. The resultant pinning force density is proportional to an elementary pinning strength and obeys a linear summation. The obtained scaling law of the pinning force density coincides approximately with experimental results on irradiated Nb specimens. Quantitative agreements with experiments also seem to be satisfactory.

Recently staggered pin arrays are introduced for modern designs with high pin density. Although some studies have been done on escape routing for hexagonal arrays, the hexagonal array is only a special kind of staggered pin array. There exist other kinds of staggered pin arrays in current industrial designs, and the existing works cannot be extended to solve them. In this paper, we study the escape routing problem on staggered pin arrays. Network flow models are proposed to correctly model the capacity constraints of staggered pin arrays. Our models are guaranteed to find an escape routing satisfying the capacity constraints if there exists one. The correctness of these models lead to an optimal algorithm.

Based on the theory of current and potential distribution for aqueous solution systems and existing analytical models, tertiary current and potential distributions over carbon and non-consumable anodes in cryolite-alumina melt are calculated. By varying different electrolysis parameters and anode surface geometry (rectangular smooth anode and section of anode sinusoidal profile), their functional relationship with current and potential distribution is established. The influence of resulting distribution pattern and the values of local current density and local anode potential on anode process stability together with related probable causes of the increased consumption of carbon and non-consumable anodes are discussed. The main factors influencing on current and potential distribution are anode overpotential and diffusion layer thickness, which represents the electrolyte properties related to electrolyte mixing conditions. Local current density on the edges of a rectangular anode is 2 times higher than in the central part. Current distribution over rough anode surface is uneven—local current density at peaks of surface defects is higher by 40% to 60%. When limiting current density is approached at these preferential spots, the values of standard potentials for perfluorocarbons evolution on carbon anodes and metal fluorides formation on inert anodes are reached. The theoretically established relationship between the anode surface structure and current and potential distribution could be the primary cause for increased anode consumption and passivation with subsequent destabilization of electrolysis in standard and low-melting electrolytes. The possible ways to equalize the current and potential distribution across the anode surface are presented.

The uplift-restricted and slip-permitted (URSP) connector is a new type of connector used in steel–concrete composite structures that has been proven to improve the structural performance of negative moment regions. Since this connector changes the interface restraint between the slab and steel beam, there is an imperative to study the seismic performance of steel–concrete composite frame systems with this new type of connector. In this study, the dynamic behavior of composite frame structures with URSP connectors under seismic loads was numerically investigated. First, a beam–shell mixed model was used and complex interfaces of different connectors were considered while establishing a numerical model to conduct elasto–plastic time history analysis under various seismic loads. This numerical model was validated with the frame sub-assemblage experimental results of quasi-static cyclic tests. Second, the model analysis results of structures with URSP connectors were obtained and compared with those of traditional structures. Third, dynamic response results including roof displacement, inter-story displacement, and the distribution and failure modes of plastic hinges were analyzed and compared. The comparisons indicated that the arrangement of full-span URSP connectors had a non-negligible influence on the dynamic behavior of the systems. The arrangement increased the maximum inter-story displacement by 31.5% and induced adverse effects in certain cases, which is not suggested in the application of URSP connectors. The partial arrangement of URSP connectors had little influence on the dynamic behavior of the systems, and the frame systems still showed a good seismic performance, which was the same as the traditional composite structural system. These findings may promote the application of URSP connectors in composite structures.

Plasticity model for partially prestressed concrete

The current practice to assure composite action foresees the usage of headed studs. This type of mechanical shear connectors was developed for composite beams and only adopted for the column’s usage. Application in composite columns could lead to a reduced economy, especially for heavy composite columns used in high-rise buildings. A new type of flat shear connectors was developed and characterized that allows for fully automatic application process. This secures an increased safety of the whole structure, improved performance, optimized cross-section, reduced manufacturing time and costs. The presented paper gives a short description about the development process and focuses on the proposed analytical model describing the resistance of flat shear connectors. The developed analytical model comprises the complex stress state, which is present in the highly confined concrete directly under the connectors. The assumptions and theoretical models were confirmed in complex non-linear FE simulations performed in the Abaqus software.

A 400kN magnetorheological damper (MR damper) for a real base-isolated building was developed and its dynamic characteristics were verified by experimental tests. The MR damper has 950mm (+/-475mm) stroke and by-pass flow potion. A new type of Magneorheological fluid is also developed in order to apply to the MR damper. MR fluid had a property of the settlement of particles in dampers. Authors developed a new MR fluid, which keeps the particles in the fluid adequately enough for usual use of MR damper. Analytical model was discussed in this paper. The force by the bingham visco-plastic model was compared with the results of experimental tests. It was found that this analytical model is useful to predict the capacity of the MR damper.

Increasing IC complexity is placing new demands on multichip module (MCM) test engineers. Traditional bed of nails and flying test methods are not adequate to meet the demands of high pin count and density. Design tools need to keep pace with new test methods being employed to address this rising complexity. One approach to solving this problem is the use of a membrane test head. This paper discusses the design software requirements and CAD challenges that result from the membrane approach to substrate test. Some of these new challenges include data translation, test probe assignment and optimization, routing, and inner layer testing. The test methods and design requirements discussed are applicable to multichip, few-chip and ball grid array (BGA) packaging.

Axial flux magnetic-geared double-rotor machines (AMGDRMs) are characterized as a potential core component of the power splitting system in hybrid electric vehicles (HEVs). Conventional AMGDRMs suffer from low mechanical strength due to high axial magnetic force. In this paper, an interior-modulating-rotor axial flux magnetic-geared double-rotor machine (IMR-AMGDRM) is proposed to solve this problem. An analytical model of the IMR-AMGDRM is proposed to predict the magnetic field distribution and electromagnetic performances. Since analytical model is based on 2-D geometry, a 2-D approximation of IMR-AMGDRM which has similar output performance to 3-D finite element analysis (FEA) is presented based on the permanent magnet (PM) magnetic energy equivalent principle. Utilizing subdomain method, the magnetic field distribution and electromagnetic performances are calculated. Finally, the accuracy of the proposed analytical model is validated by 3-D FEA.Index Terms—Analytical model, axial flux, magnetic-geared machine, double-rotor machine.I. IntroductionAxial flux magnetic-geared double-rotor machines (AMGDRMs), which enable high torque density, have been considered a promising candidate for power splitting in hybrid electric vehicles (HEVs) [1]. However, conventional AMGDRMs suffer from low mechanical strength due to high axial magnetic force. To enhance mechanical strength, an interior-modulating-rotor axial flux magnetic-geared double-rotor machine (IMR-AMGDRM) which can reduce axial magnetic force dramatically is proposed in this paper. Fig. 1 (a) and (b) illustrate the configuration of the proposed IMR-AMGDRM.As axial flux type machine, IMR-AMGDRMs have complex 3-D magnetic circuits. 3-D finite element analysis (FEA) can offer accurate results by taking into account the nonlinear factors such as magnetic saturation and flux leakage. But the major drawback of 3-D FEA is serious time cost. Analytical model which is much lower time-consuming provides an alternative for electromagnetic performance prediction in the initial design procedure.In this paper, an analytical model of the IMR-AMGDRM is proposed. The geometry of analytical model is derived based on PM magnetic energy equivalent principle to guarantee similar output performance to 3-D FEA. The solution to analytical model is calculated by subdomain method. To evaluate the accuracy of the proposed analytical model, the results computed by analytical model and that of 3-D FEA are compared.II. Configuration of IMR-AMGDRMIn conventional configuration, the inner and outer rotors are the permanent magnet (PM) rotor and the modulating rotor, respectively. Since the modulating rotor is closer to the PM rotor than stator, the modulating rotor suffers from high axial magnetic force. Furthermore, the modulating rotor is hollow and thus the low mechanical strength of modulating rotor becomes the major drawback of conventional configuration [1]. To solve this problem, the IMR-AMGDRM which switches positions of the PM rotor and the modulating rotor is proposed. In interior-modulating-rotor configuration, as shown in Fig. 1 (a) and (b), the PM rotor is between the modulating rotor and stator, i.e. the inner and outer rotors are the modulating rotor and the PM rotor, respectively. Owing to that the PM rotor suffers from reverse axial magnetic forces from both sides simultaneously, the total axial magnetic force is dramatically reduced. Hence, although the outer rotor is hollow in both configurations, the axial magnetic force of interior-modulating-rotor configuration is significantly decreased, leading to higher mechanical strength and reliability.III.Geometry of 2-D ApproximationGenerally, the unrolled section of axial flux machine at mean radius is used as 2-D approximation. However, few references are found to evaluate the electromagnetic performance equivalence of such approximation. To make the electromagnetic performance of 3-D model and 2-D approximation equal, the amount of magnetic energy of the PM should remain unchanged after approximation, i.e. PM magnetic energy equivalent principle [2]. A 2-D approximation of IMR-AMGDRM which has identical output performance is presented by using PM magnetic energy equivalent principle.IV. Analytical Calculation of IMR-AMGDRMThe proposed analytical model is illustrated in Fig. 1 (c). It can be seen that the model consists of four subdomains. Region i, I, II and III represent the ith slot of the modulating rotor, the inner air gap, the PM rotor and the outer air gap, respectively. Utilizing subdomain method, the magnetic field distributions in the inner and outer air gaps are obtained by the solution of Laplace’s and Poisson’s equations. Then, the electromagnetic performances such as no-load back EMF, torque and axial force can be derived from the calculated magnetic field distributions.Comparisons of computation accuracy between analytical model and 3-D FEA is shown in Fig. 2. As can be observed, the results of analytical model are well consistent with that of 3-D FEA, validating the proposed method. **

Analytical model based performance evaluation, sizing and coupling flow optimization of liquid desiccant run-around membrane energy exchanger systems

An X-band tunnel diode amplifier (TDA) has been studied for SGEMP response. This study has involved analytical modeling and predictions, tunnel diode electrical pulsing to develop damage statistics, and experimental measurements in an 800 kvp flash X-ray environment. In contrast to photocurrent limited TREE response, significant SGEMP replacement currents can flow through the tunnel diode. This response is associated with mechanical design, the use of gold-plated conductors facing aluminum surfaces within a cavity with corresponding photoemission differences and the differences in fore and back emission between the tunnel diode amplifier and the evacuated test chamber walls. The SGEMP current is independent of bias circuit design. The modeling and prediction effort included SGEMP current determination, electrical circuit modeling and computerized transient radiation circuit analysis. The experimental SGEMP tests were performed in vacuum using the BLACK-JACK 3 (BJ3) facility at Maxwell Laboratories, Inc., in San Diego, California. Measurements are reported for the current responses of the tunnel diode and the circulator. Eight tunnel diodes were damaged due to SGEMP and their damage threshold energies were calculated, using tunnel diode characteristics, radiation dose and SGEMP currents. Damage frequency data for the BJ3 tests correlates with separate electrical pulse data and supports the conclusion that the SGEMP response of TDA's is predictable using the model developed in this study.