Modeling and Flight Data Analysis of Spacecraft Dynamics with a Large Solar Array Paddle

The Advanced Land Observing Satellite (ALOS) was launched on January 24 2006 and has been operated successfully since then. This satellite has the attitude dynamics characterized by three large flexible structures, four large moving components, and stringent attitude/pointing stability requirements. In particular, it has one of the largest solar array paddles. Presented in this paper are flight data analyses and modeling of spacecraft attitude motion induced by the large solar array paddle. On orbit attitude dynamics was first characterized and summarized. These characteristic motions associated with the solar array paddle were identified and assessed. These motions are thermally induced motion, the pitch excitation by the paddle drive, and the role excitation. The thermally induced motion and the pitch excitation by the paddle drive were modeled and simulated to verify the mechanics of the motions. The control law updates implemented to mitigate the attitude vibrations are also reported

constant pressure expression of power law non-newtonian fluid/solid mixture

Expression is the separation of liquid from a two-phase solid/liquid system by compression due to movement of the retaining wall. Expression of non-Newtonian fluid/solid mixture is often encountered in the fields of polymer and food industries. However, a reliable method for the design of the expression process has not been established. In this study, we conducted expression experiments of non-Newtonian fluid/solid mixture under a constant pressure condition. As a model suspended particle, cellulose or kieselguhr powder was used. The powder was mixed with an aqueous solution of sodium carboxymethyl cellulose or sodium polyacrylate. The mixture was first preconsolidated in the compression-permeability cell that consisted of a cell cylinder and a piston of 6 cm diameter and then expressed under constant pressure. As the expression advanced, the time course of the thickness of the sample was measured by a dial gauge fitted on the cylinder. The basic consolidation equation was derived by combining the fundamental equation for power law non-Newtonian flow in the cake with the equation of continuity, and was solved numerically using the Runge-Kutta method. The progress of the expression is represented by an average consolidation ratio Uc. The agreement between calculated and experimental Uc was satisfactory when the creep deformation of the material was taken into consideration. It was elucidated that the consolidation time required for attaining a certain degree of primary consolidation depends on the (N+1)/N-th power of the total volume of the solid material , where N is the flow behavior index of the squeezed liquid. On the other hand, the creep constants B, the ratio of creep deformation to the total deformation, and , a measure of the rate of creep deformation, both were found to be -independent parameters, supporting the validity of the assumption made in the theoretical derivation

Constant pressure expression of power law non-Newtonian fluid/solid mixture

Expression of non-Newtonian fluid/solid mixture is often encountered in the fields of polymer and food industries. However, a reliable method for the design of the expression process has not been established. In this study, we conducted expression experiments of power law non-Newtonian fluid/solid mixture under constant pressure condition. The basic consolidation equation was derived by combining the fundamental equation for power law non-Newtonian flow through the cake with the equation of continuity and solved numerically using the Runge-Kutta method. The progress of the expression is represented by an average consolidation ratio Uc. The agreement between calculated and experimental Uc was satisfactory when the creep deformation of the material was taken into consideration. It was also elucidated that the consolidation time required for attaining a certain degree of primary consolidation depends on the (N+1)/N-th power of the total volume of the solid material omega_0, where N is the flow behavior index of the squeezed liquid. On the other hand, the creep constants B, the ratio of creep deformation to the total deformation, and eta, a measure of the rate of creep deformation, both were found to be omega_0-independent parameters, supporting the validity of the assumption made in the theoretical derivation

Current Status and Future Development of Cell Transplantation Therapy for Periodontal Tissue Regeneration

It has been shown that stem cell transplantation can regenerate periodontal tissue, and several clinical trials involving transplantation of stem cells into human patients have already begun or are in preparation. However, stem cell transplantation therapy is a new technology, and the events following transplantation are poorly understood. Several studies have reported side effects and potential risks associated with stem cell transplantation therapy. To protect patients from such risks, governments have placed regulations on stem cell transplantation therapies. It is important for the clinicians to understand the relevant risks and governmental regulations. This paper describes the ongoing clinical studies, basic research, risks, and governmental controls related to stem cell transplantation therapy. Then, one clinical study is introduced as an example of a government-approved periodontal cell transplantation therapy

Dewatering of slurry with poor filterability in basket centrifuge: discharge of supernatant using bypass filter medium

When centrifugal dewatering in basket centrifuge involves the sedimentation of particles in feed slurry, the slurry separates into two phases: supernatant and cake. The dewatering proceeds as the supernatant permeates through the cake. However, if the cake formed has poor permeability, it takes longer time to reach the desired moisture content. In this study , a new method is proposed to dewater slurry which forms cake with poor permeability and a comparison was made with the conventional design. In the proposed design, the filter media is placed not only on the circuit, but also at the bottom of the filter chamber. Thus, even though the cake formed has a high hydrodynamic resistance, the supernatant could be discharged because the filter medium at the bottom has less hydrodynamic resistance than the cake and therefore works as a bypass. It is known from the previous study that when the supernatant is totally discharged, the cake will undergo a consolidation process, which will make the cake more compact. Therefore, it is postulated that the bypass filter medium would improve the dewatering efficiency drastically. The results obtained is that the supernatant still remained in the filter chamber even after 300 s of dewatering when the conventional design was used, while the supernatant was completely discharged within 150 s when the new design was used. Thus, it can be concluded that the filter medium at the bottom of the filter chamber worked as a bypass and improved the dewatering performance

Electrostatic Discharge Ground Test of a Polar Orbit Satellite Solar Panel

The Advanced Land Observing Satellite that was launched by the Japan Aerospace Exploration Agency in 2006 carries a large solar-array paddle of 22 times 3 m in polar orbit. The wake side of the solar paddle can be charged to a negative value exceeding -1000 V. Numerical simulations and laboratory experiments are carried out to investigate charging and arcing phenomena on the backside of the solar paddle that has exposed bypass diode boards and silver-Teflon thermal film. Possibility of secondary arc and surge voltage between hot and return ends of power circuit has been investigated. The authors irradiate solar-panel coupons with an electron beam to simulate charging situation near the North Pole. Surface flashover is observed once the insulator potential exceeds -7000 V. The authors have also tested charging situation near the South Pole where carbon fiber-reinforced plastics surface facing dense ionospheric plasma may arc easily once a satellite potential drops to -80 or -90 V. The solar-paddle design has been modified to increase the safety margin against arcing, and tests have been carried out to identify the strength limit under extremely harsh test environment

Analysis of stepwise expression of sake fermentation broth

In the sake brewing, expression is used for the separation of liquid from the fermentation broth. Although the period of expression has to be as short as possible in order to prevent the sake from losing flavour, practically it takes much time to complete expression because of the highly compressible materials (e.g. proteins and starch) in the broth. For the expression of highly compressible materials, it is known empirically that the applied pressure should be low at the beginning of the expression and increased stepwise as the expression proceeds. In this study, we propose a method for the analysis of stepwise expression of highly compressible materials. The fermentation broth of sake was used as the experimental material. The experimental apparatus of constant pressure expression utilised in this study essentially consists of a vertical cylinder with a movable piston. The change in thickness of the material in the cylinder with the time was measured by a dial gauge. The mechanism of liquid removal is filtration at the beginning of expression, followed by consolidation. The filtration rate can be obtained by applying Ruth’s constant pressure filtration theory. In the consolidation period (i.e. after the end of the filtration), the deliquoring rate is calculated by the numerical analysis of the basic consolidation equation. However, because the formula expressing the distribution of solid compressive pressure pS of a filter cake with highly compressible materials has not been established well, the consolidation equation cannot be solved analytically. We therefore propose a new empirical equation representing the pS-distribution of a filter cake with highly compressible materials. The equation proposed in this study makes it possible to analyse the stepwise expression of highly compressible materials

RAISE-2 for Agile On-Orbit Demonstration of Innovative Satellite Technologies: Program Strategy, Mission Definition, and Preliminary Design

The Japan Aerospace Exploration Agency (JAXA) has provided the second demonstration opportunity of the Innovative Satellite Technology Demonstration Program. In this second mission, JAXA develops the Rapid Innovative Payload Demonstration Satellite-2 (RAISE-2) that carries six components and parts as on-orbit demonstration themes. This paper presents an overview of the RAISE-2’s demonstration themes, mission definition including standard platform specifications, results of Phase-A study and preliminary design