A survey of advanced battery systems for space applications

The results of a survey on advanced secondary battery systems for space applications are presented. Fifty-five battery experts from government, industry and universities participated in the survey by providing their opinions on the use of several battery types for six space missions, and their predictions of likely technological advances that would impact the development of these batteries. The results of the survey predict that only four battery types are likely to exceed a specific energy of 150 Wh/kg and meet the safety and reliability requirements for space applications within the next 15 years

A survey of advanced battery systems for space applications

The results of a survey on advanced secondary battery systems for space applications are presented. The objectives were: to identify advanced battery systems capable of meeting the requirements of various types of space missions, with significant advantages over currently available batteries, to obtain an accurate estimate of the anticipated improvements of these advanced systems, and to obtain a consensus for the selection of systems most likely to yield the desired improvements. Few advanced systems are likely to exceed a specific energy of 150 Wh/kg and meet the additional requirements of safety and reliability within the next 15 years. The few that have this potential are: (1) regenerative fuel cells, both alkaline and solid polymer electrolyte (SPE) types for large power systems; (2) lithium-intercalatable cathodes, particularly the metal ozides intercalatable cathodes (MnO2 or CoO2), with applications limited to small spacecrafts requiring limited cycle life and low power levels; (3) lithium molten salt systems (e.g., LiAl-FeS2); and (4) Na/beta Alumina/Sulfur or metal chlorides cells. Likely technological advances that would enhance the performance of all the above systems are also identified, in particular: improved bifunctional oxygen electrodes; improved manufacturing technology for thin film lithium electrodes in combination with polymeric electrolytes; improved seals for the lithium molten salt cells; and improved ceramics for sodium/solid electrolyte cells

Development of new sealed bipolar lead-acid battery

New light weight composite bipolar plates which can withstand the corrosive environment of the lead acid battery have made possible the construction of a sealed bipolar lead acid battery that promises to achieve very high specific power levels and substantially higher energy densities than conventional lead acid batteries. Performance projections based on preliminary experimental results show that the peak specific power of the battery can be as high as 90 kW/kg, and that a specific power of 5 kW/kg can be sustained over several thousand pulses

Novel Method for Improving the Capacity of Optical MIMO System Using MGDM

In current local area networks, multimode fibers (MMFs), primarily graded index (GI) MMFs, are the main types of fibers employed for data communications. Due to their enormous bandwidth, it is considered that they are the main channel medium that can offer broadband multiservices using optical multiplexing techniques. Amongst these, mode group diversity multiplexing (MGDM) has been proposed as a way to integrate various services over an MMF network by exciting different groups of modes that can be used as independent and parallel communication channels. In this paper, we study optical multiple-input–multiple-output (O-MIMO) systems using MGDM techniques while also optimizing the launching conditions of light at the fiber inputs and the spot size, radial offset, angular offset, wavelength, and the radii of the segment areas of the detectors. We propose a new approach based on the optimization of launching and detection conditions in order to increase the capacity of an O-MIMO link using the MGDM technique. We propose a (3 $times$ 3) O-MIMO system, where our simulation results show significant improvement in GI MMFs' capacity compared with existing O-MIMO systems. Optical multiple-input-multiple-output multiplexing of parallel communication multichannels over a single multimode fiber network. Optical multiple-input-multiple-output multiplexing of parallel communication multichannels over a single multimode fiber network

A Study of the Turbulent Flows in Sloping and Adversely Sloping Rectangular Culverts

In this paper, an experimental investigation was carried out to study the turbulent flows and flow characteristics through sloping and adversely sloping rectangular culverts in a rectangular channel of constant width using Laser Doppler Velocimetry (LDV). Also, experimental study was carried out to investigate the characteristics of the hydraulic jump occurring in a sloping and adversely sloping rectangular culvert with pressurized flow downstream from the jump and a submerged culvert outlet. Experiments were conducted on a culvert with relatively small slopes to study the variation of the relative tailwater depth with the main parameters affecting the jump in sloping and adversely sloping culverts. These parameters include the channel bottom slope, the initial Froude number and the ratio of the initial depth to culvert height. To study the turbulence characteristics, precise and accurate measurements of the mean fluctuating flow quantities such as streamwise and vertical mean velocity components, and streamwise and vertical turbulence intensity components and turbulence shear stress were carried out. Also, this paper presents the results of a Laser Doppler Velocimetry study of hydraulic jumps in a culvert with different relative tailwater depths and different initial Froude numbers. The characteristics of hydraulic jumps were discussed and analyzed. Non– dimensional design curves were provided to relate the jump characteristics. The maximum vertical velocity in the recirculating zone for all jumps is about 6% of the initial velocity. The results show that the maximum streamwise velocity near the center plane was smaller than that near the side wall. The turbulence shear stress near the center was about (35-45)% higher than that near the side wall. After the jump, the flow will recover into a two-dimensional flow

Creating movable interfaces by micro-powder injection moulding

This paper presents a novel in situ technique to produce articulated components with high-precision, micro-scale movable interfaces by micro-powder injection moulding (μPIM). The presented process route is based on the use of micro-scale sacrificial layer between the movable subcomponents which is eliminated during the debinding step, creating a dimensionally-controlled, micro-scale mobile interface. The fabrication technique combines the advantages of micro-powder overmoulding, catalytic debinding and sintering. The demonstrated example was a finger bone prosthesis joint consisting of two sub-components with an interface between components of 200 μm in size. The geometries of the sub-components were designed such that they are inseparable throughout the process whilst allowing them to move relative to each other after the debinding stage. The components produced showed the feasibility of the process route to produce readily-assembled meso-, and potentially micro-, scale articulated system

Surface Integrity of Holes Machined by Orbital Drilling of Composites with Single Layer Diamond Tools

AbstractOrbital drilling of composites was investigated to observe hole surface integrity in terms of surface roughness, delamination, surface burning, and geometric accuracy. Experiments were conducted with a brazed single layer diamond tool of ball-end geometry to drill 220 holes. Cutting forces and temperatures were measured. Micro-observations were made of the hole surface. The results showed that the forces increased sharply during drilling of the first 44 holes followed by a gradual rise. Part temperatures varied between 98-184°C. Surface roughness Ra varied from 13-17μm. Almost 99% of the holes were drilled without exit delamination; however, 2.3% of the holes showed entrance delamination

The potential implication of eosinophil activation in the pathogenesis of childhood asthma

Background: Asthma is now recognized as an eosinophil mediated inflammation of the airways. Pulmonary function tests are less easily performed in young children. So, measuring markers of eosinophil activation is of special importance in pediatric practice. Objective: This study aimed at evaluating the role of eosinophil protein X (EPX) as a marker for assessment of asthma attack severity and control of the exacerbation. Methods: Serum EPX was measured in 35 asthmatic Egyptian children aged between 7 and 10 and 35 age and sex matched healthy children using radioimmunoassay technique (RIA). Asthmatic patients were graded according to severity of the attack into mild, moderate and severe and the measurement was performed during and after the resolution of acute asthma attack. In addition, complete hemogram, total serum IgE, arterial blood gases and stool analysis were performed and peak expiratory flow rate (PEFR) was assessed in asthmatic children during and after acute exacerbation. Results: Serum concentrations of EPX, total serum IgE and absolute eosinophilic count (AEC) were significantly higher in asthmatic children than healthy controls (P < 0.001). Serum EPX and AEC were significantly higher in all studied groups before treatment compared to the corresponding levels of the same patients after treatment (P < 0.001). Total serum IgE was significantly higher only in mild and moderate asthma before treatment (P < 0.001). Serum EPX level was significantly elevated among patients with severe attacks (84.70 ± 7.18 μg/L) than those with moderate attacks (67.2 ± 5.31 μg/L) and patients with mild attacks (53.47 ± 11.47 μg/L)(P < 0.001). It was negatively correlated to PEFR measurement during attacks (r=-0.75, P < 0.05). A significant reduction in serum EPX and AEC was observed after the resolution and improvement of pulmonary function. Meanwhile, total serum IgE decreased after treatment with the resolution of asthma attack, yet it remained significantly higher than that of controls (P < 0.001). Conclusion: Our findings support the concept that EPX may be implicated in the pathogenesis of asthma and highlights its importance in monitoring the severity and control of asthma exacerbation. Hence, it might represent an objective guide of treatment efficacy. Keywords: EPX, Childhood asthma, pathogenesis, eosinophil activationEgypt J Pediatr Allergy Immunol 2004; 2(1): 52-5

Method for forming thin composite solid electrolyte film for lithium batteries

A composite solid electrolyte film is formed by dissolving a lithium salt such as lithium iodide in a mixture of a first solvent which is a cosolvent for the lithium salt and a binder polymer such as polyethylene oxide and a second solvent which is a solvent for the binder polymer and has poor solubility for the lithium salt. Reinforcing filler such as alumina particles are then added to form a suspension followed by the slow addition of binder polymer. The binder polymer does not agglomerate the alumina particles. The suspension is cast into a uniform film

A mapping approach to synchronization in the "Zajfman trap". II: the observed bunch

We extend a recently introduced mapping model, which explains the bunching phenomenon in an ion beam resonator for two ions [Geyer, Tannor, J. Phys. B 37 (2004) 73], to describe the dynamics of the whole ion bunch. We calculate the time delay of the ions from a model of the bunch geometry and find that the bunch takes on a spherical form at the turning points in the electrostatic mirrors. From this condition we derive how the observed bunch length depends on the experimental parameters. We give an interpretation of the criteria for the existence of the bunch, which were derived from the experimental observations by Pedersen et al [Pedersen etal, Phys. Rev. A 65 042704].Comment: 25 pages, 6 figures; added new section 5 and clarified text; submitted to J. Phys.