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Search Results: 1 - 10 of 732 matches for " Shigeru Shimose "
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Supersonic Flutter Utilization for Effective Energy-Harvesting Based on Piezoelectric Switching Control
Kanjuro Makihara,Shigeru Shimose
Smart Materials Research , 2012, DOI: 10.1155/2012/181645
Abstract: The harvesting of electrical energy generated from the flutter phenomenon of a plate wing is studied using the quasi-steady aerodynamic theory and the finite element method. The example of supersonic flutter structure comes from sounding rockets’ wings. Electrical energy is harvested from supersonic flutter by using piezoelectric patches and switching devices. In order to evaluate the harvesting performance, we simulate flutter dynamics of the plate wing to which piezoelectric patches are attached. We demonstrate that our harvesting system can generate much more electrical energy from wing flutter than conventional harvesting systems can. This flutter utilization changes our perception to a useful one in various fruitful applications from a destructive phenomenon. 1. Introduction Flutter is caused by the interaction between the structural motion of a wing and the aerodynamic load exerted on the wing. It is a typical self-excited aeroelastic phenomenon that occurs in wings, thin walls, and so on. Dowell [1] occurs most frequently within a high-speed, that is, transonic, supersonic, and hypersonic flow. Lottati [2] investigated the effects of structural and aerodynamic damping on the speed of flutter of a composite plate wing. Tang and Dowell [3] have analyzed the nonlinear behavior of a flexible rotor blade due to structural free-play and aerodynamic stall nonlinearities. The analytical results were compared with experimental observations. Various studies have been conducted on flutter dynamics, such as prediction of flutter and robust structural optimization of wings [4]. The use of sophisticated smart materials such as piezoelectric materials, shape memory alloys, and magnetostrictive materials in aerospace engineering can lead to the development of new design concepts. A new design concept is to alter structural dynamics by exertion of force or deformation. Moon and Hwang [5] used the linear quadratic regulator theory to suppress nonlinear panel flutter. Han et al. [6] designed a mu-synthesis controller to enhance flutter suppression performance despite parametric uncertainties. Raja et al. [7] used multilayer piezoelectric actuators and piezoelectric sensors for constructing a linear quadratic Gaussian controller to suppress the flutter of a composite plate. Agneni et al. [8] applied this passive method to flutter suppression and demonstrated satisfactory suppression performance. However, flutter suppression performance achieved by adopting this passive method is poorer when the electrical resonance frequency is slightly different from the frequency
Comparison of Analog and Digital Self-Powered Systems in Multimodal Vibration Suppression
Shigeru Shimose,Kanjuro Makihara,Junjiro Onoda
Smart Materials Research , 2012, DOI: 10.1155/2012/287128
Abstract: This paper compares our analog and digital self-powered systems for vibration suppression, and shows experimental results of multimodal vibration suppression for both self-powered systems. The experimental results are evaluated in light of the damping performance and adaptability under various vibrational conditions. We demonstrate various examples of our innovative vibration suppression method, called “digital self-powered.” Proper status switching of an electric circuit made up of an inductor and a selective switch connected to a piezoelectric transducer attenuates the vibrations. The control logic calculation and the switching events are performed with a digital microprocessor that is driven by the electrical energy converted from the mechanical vibration energy. Therefore, this vibration suppression system runs without any external power supply. The self-powering feature makes this suppression method useful in various applications. To realize an ideal vibration suppression system that is both self-powered and effective in suppressing multimode vibration, sophisticated control logic is implemented in the digital microprocessor. We demonstrate that our digital self-powered system can reduce the vibrational displacements of a randomly excited multimodal structure, by as much as 35.5%. 1. Introduction Vibration control methods are roughly categorized into two groups, that is, active and passive methods [1–4]. Active vibration control methods usually yield high-performance vibration suppression [1, 2]. However, active control systems may become unstable if the control is improperly designed. In addition, active vibration control systems need an external energy supply to suppress vibrations. On the other hand, passive vibration control methods use energy dissipative mechanisms such as dampers, frictional devices, and electric resistors [3, 4]. Because passive approaches do not need an energy supply they are always stable. Passive methods are easier to implement in actual systems than are the more complicated active methods, because they do not need controllers, sensors, or filters. However, in most cases, passive systems do not provide a satisfactory vibration suppression performance. In general, the majority of passive systems suppress vibrations well only in expected situations such as those regarding natural frequency and temperature. Typical examples of less robustness of frequency alternation are mechanically tuned mass dampers and electrical dynamic vibration absorbers. There are research papers that compare the performance of semiactive and passive
Energy Harvesting Using an Analog Circuit under Multimodal Vibration
Shigeru Shimose,Kanjuro Makihara,Junjiro Onoda
Smart Materials Research , 2013, DOI: 10.1155/2013/736487
Energy Harvesting Using an Analog Circuit under Multimodal Vibration
Shigeru Shimose,Kanjuro Makihara,Junjiro Onoda
Smart Materials Research , 2013, DOI: 10.1155/2013/736487
Abstract: The efficiency of harvesting energy from a vibrating structure using a piezoelectric transducer and a simple analog circuit is investigated experimentally. This analog circuit was originally invented for a synchronized switch damping on inductor (SSDI) technique, which enhances the damping of mechanical vibration. In this study, the circuit is used to implement a synchronized switch harvesting on inductor (SSHI) technique. A multiple degree of freedom (MDOF) structure is excited by single sinusoidal forces at its resonant frequencies and by random forces. The piezoelectric transducer converts this mechanical energy into electrical energy which is harvested using a standard rectifier bridge circuit with and without our analog circuit. Experimental results show that our analog circuit makes it possible to harvest twice as much energy under both single sinusoidal and random vibration excitations. 1. Introduction Energy harvesting techniques have been studied extensively in recent years. Energy harvesting is a process by which energy is captured and stored. Energy can be harvested from various power sources, including wind power, solar power, ocean tides, heart, magnetic fields, and structural vibrations. We focused on the vibration energy of a structure, using the piezoelectric effect to convert structural vibration energy into electrical energy. There is substantial research on this technique, as reviewed by Sodano et al. [1]. Lesieutre et al. [2] addressed the damping associated with energy harvesting from structural vibrations. Badel et al. [3–5] proposed a synchronized switch harvesting on inductor (SSHI) technique to improve energy harvesting. SSHI is based on vibration suppression technique named synchronized switch damping on inductor (SSDI). Both SSHI and SSDI use a piezoelectric transducer attached to the structure and connected to an inductive circuit having an on-off switch [6–10]. The switch in the circuit is flipped at each extremum of displacement of the structure. A displacement sensor and a controller are needed to synchronize the switching commands with the mechanical vibration. In a self-powered system, these sensors and controllers need to be driven using a fraction of the harvested energy. We previously invented an analog circuit that automatically performs switching without an external energy source [11]. We describe in this paper how this analog circuit enhances the energy harvesting performance when used with SSHI. Although many studies [12–14] have been conducted on SSHI, most of them are limited to the sinusoidal vibration of a
Assessment of Electrical Influence of Multiple Piezoelectric Transducers' Connection on Actual Satellite Vibration Suppression
Shigeru Shimose,Kanjuro Makihara,Kenji Minesugi,Junjiro Onoda
Smart Materials Research , 2011, DOI: 10.1155/2011/686289
Abstract: We conduct comprehensive investigation of a semiactive vibration suppression method using piezoelectric transducers attached to structures. In our system, piezoelectric transducers are connected to an electric circuit composed of the diodes, an inductance, and a selective switch. Our method (SSDI) makes better use of counterelectromotive force to suppress the vibration, instead of simple dissipation of vibration energy. We use an actual artificial satellite to verify their high performance compared to conventional semi-active methods. As a consequence, we demonstrate that our semi-active switching method can suppress the vibration of the real artificial satellite to as much as 50% amplitude reduction. In our experiment, we reveal that the suppression performance depends on how multiple piezoelectric transducers are connected, namely, their series or parallel connection. We draw two major conclusions from theoretical analysis and experiment, for constructing effective semi-active controller using piezoelectric transducers. This paper clearly proves that the performance of the method is the connection (series or parallel) of multiple piezoelectric transducers and the their resistances dependent on frequency. 1. Introduction Space structures, such as the space station or artificial satellites, are built for the purpose of highly demanding space missions. Large solar paddles and bulky antennas are necessary for the space missions. However, since the launch ability of rockets strictly limits the payload weight, space structures have to extremely minimize their weight, which results in the use of flexible structures and spindly members. Therefore, they are more prone to vibrations compared with structures on earth with less weight restriction. Moreover, space structures and artificial satellites are exposed to severe vibration environment at the launch stage. The relaxation of such a severe condition is an important issue in order to improve their reliability and to reduce their development costs. Many methods of vibration suppression have been studied and proposed [1–6]. There is currently a large effort underway to effectively suppress the vibration of structures. Vibration control methods are roughly categorized into two groups, that is, active and passive methods [1–6]. Active vibration control methods usually have high performance in vibration suppression [1–3]. In the space field, the active rack isolation system (ARIS) [1] of the International Space Station is famous as the active vibration control system composed of eight voice-coil actuators in order
Seismic Damage Estimation of an Actual Reinforced Concrete Structure Using Subset MCMC  [PDF]
Shigeru Kushiyama
Open Journal of Civil Engineering (OJCE) , 2013, DOI: 10.4236/ojce.2013.33016

To estimate seismic damage of structures under strong motions is very important to know true safety of structures. However, we have to deal with very small failure probability issue to investigate quantitatively. If we use standard MCS (Monte Calro Simulation) to discuss failure probability, e.g., 1 × 10-6 order, since we have to execute nonlinear dynamic response analyses of approximate 107 times, it is not realistic. Recently, a subset simulation, which reduces the computation time by replacing small failure probability into the product of conditional failure probabilities, was proposed. In this study, the subset simulation is applied to estimate failure probability of an actual reinforced concrete building with 11 stories, and discuss the safety of the structure by checking with design criteria.

Spin-Magnetic Moment of Dirac Electron, and Role of Zitterbewegung  [PDF]
Shigeru Sasabe
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.57064

The spin-magnetic moment of the electron is revisited. In the form of the relativistic quantum mechanics, we calculate the magnetic moment of Dirac electron with no orbital angular-momentum. It is inferred that obtained magnetic moment may be the spin-magnetic moment, because it is never due to orbital motion. A transition current flowing from a positive energy state to a negative energy state in Dirac Sea is found. Application to the band structure of semiconductor is suggested.

A Bivariate Software Reliability Model with Change-Point and Its Applications  [PDF]
Shinji Inoue, Shigeru Yamada
American Journal of Operations Research (AJOR) , 2011, DOI: 10.4236/ajor.2011.11001
Abstract: Testing-time when a change of a stochastic characteristic of the software failure-occurrence time or software failure-occurrence time-interval is observed is called change-point. It is said that effect of the change-point on the software reliability growth process influences on accuracy for software reliability assessment based on a software reliability growth model (SRGM). We propose an SRGM with the effect of the change-point based on a bivariate SRGM, in which the software reliability growth process is assumed to depend on the testing-time and testing-effort factors simultaneously, for accurate software reliability assessment. And we discuss an optimal software release problem for deriving optimal testing-effort expenditures based on our model. Further, we show numerical examples of software reliability assessment based on our bivariate SRGM and estimation of optimal testing-effort expenditures by using actual data.
Empirical Analysis for High Quality Software Development  [PDF]
Naomi Honda, Shigeru Yamada
American Journal of Operations Research (AJOR) , 2012, DOI: 10.4236/ajor.2012.21004
Abstract: It remains important for a development organization to configure a software process that enables it to develop software products with the least possible number of defects after shipment. A development organization of CMMI level 5 has, over three years, been strived to improve those software projects that had been noted as having many defects after shipment. In this paper, we discuss our organization’s improvement (Kaizen) activities, to analyze the important matters of software process to be considered when developing a software product with the least possible number of defects after shipment. Our results are identified by three important points; 1) early ensured quality by defect detection during design or code review; 2) quality assurance for both process quality and product one; and 3) quantitative management by which data of the appropriate resolution can be collected at an appropriate timing.
Increased Cerebral Cortex Perfusion in Stroke Patients with Cognitive Disorder Following Cilostazol Administration, Two Cases Report  [PDF]
Yukihiro Hara, Shigeru Obayashi
Neuroscience & Medicine (NM) , 2012, DOI: 10.4236/nm.2012.34043

Objective: In our search for a new augmentation therapy for stroke patients, we administered cilostazol, an antiplatelet agent. Subjects: The patients suffered from mild hemiparesis or cognitive disorder showing reduced cerebral perfusion in the prefrontal cortex. Methods: We evaluated the functional cerebral blood flow (CBF) before and after the administration of cilostazol using near-infrared resonance spectroscopy (NIRS) during a verbal fluency task (VFT). Results: For the patient with cognitive disorder, statistically significant improvements were observed in the number of generated words in the VFT before and after administration of 50 mg cilostazol (p < 0.05, Mann-Whitney U test). Another patient without cognitive disorder, however, showed no significant VFT improvement after administration of cilostazol. Effect size data revealed large or very large effects of cilostazol on brain activation (oxy-Hb levels) at the affected side prefrontal cortex for both patients. The patient with cognitive disorder showed significant improvement in VFT performance as well as an increase in bilateral prefrontal CBF after cilostazol administration. Discussion: These findings suggest that, for patients with cerebrovascular lesions suffering from cognitive disorder, cilostazol may be promising as a drug to improve cognitive function in addition to preventing recurrent cerebral infarction.

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