PROPERTIES OF A MULTI-STACK TYPE PIEZOELECTRIC ENERGY HARVESTING DEVICE

ABSTRACT

In this study, We investigated the possibility of use of multi-stack type piezoelectric devices. The dielectric and piezoelectric properties of the device were examined. To match the external vibration frequency with the device resonant frequency, the metal type manipulator was combined with the multi-stack device. Under an external force of 1 G at 120 Hz, the device exhibited a voltage of 12 V and a power of 60 mw in resonance mode.     

Analysis of glass fabric impregnation using a resin drop method

Wettability of a glass fabric was studied by use of a resin drop method. The mixing ratios of epoxy resin and anhydride hardener were adopted as 1:0.5, 1:1 and 1:1.2. A catalyst of 2-ethyl-4-methylimidazole added as much as 0.1wt% of the mixed resin. A curing analysis by differential scanning calorimeter (DSC) showed that the mixed resin could be infiltrative at room temperature. An effective contact angle and the height of the resin drop onto the glass fabric preset on a flat glass plate were measured as a function of time. The wet area of the resin drop was also measured. Behaviors of the contact angle, the drop height, the net wet area and the coefficient of wettability were analyzed in the glass fabric impregnation. The resin drop method was shown to be quite effective in evaluating the capillary-mode resin penetration into the fabric.     

Characterization of acid- and pepsin-soluble collagens from flatfish skin

Acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from flatfish skin were characterized. The yield of PSC was 85.5%, which was higher than that of ASC at 57.3%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns showed that both the ASC and PSC were consisted of α1 and α2 chains, and β-chain. According to the results of Fourier transform infrared (FTIR) spectroscopy and hydroxylation, no difference in the helical structure between ASC and PSC was found. Thermal denaturation temperature (TDT) of flatfish skin collagen was 26.6°C for ASC and 26.7°C for PSC, which were similar to those of temperate fishes, while were lower compared to tropical fishes, such as the conger eel and Nile perch. There was no solubility difference between ASC and PSC at various pH and NaCl concentrations. Therefore, PSC will be preferable compared to ASC for commercial uses because of its higher yield.     

Design and analysis of an active steering bogie for urban trains

The conventional railway vehicle was designed to ensure running stability using high stiffness elements for primary suspensions. Curving performance of the railway vehicle is relatively low because the natural steering motion of a wheelset is constrained by the high stiffness suspensions. High running stability has always been in conflict with good curving performance in conventional design processes. This conflict problem can be solved with an active steering bogie since active elements properly control the wheelset motions according to track conditions such as straight or curved lines. In this paper, an active steering mechanism for railway vehicle is introduced, and the curving performance of the proposed active steering bogie is investigated through simulation and experiments. According to the results, the proposed active steering bogie is highly effective for curve negotiation.     

An efficient dynamic response optimization using the design sensitivities approximated within the estimate confidence radius

In order to reduce the expensive CPU time for design sensitivity analysis in dynamic response optimization, this study introduces the design sensitivities approximated within estimated confidence radius in dynamic response optimization with ALM method. The confidence radius is estimated by the linear approximation with Hessian of quasi-Newton formula and qualifies the approximate gradient to be validly used during optimization process. In this study, if the design changes between consecutive iterations are within the estimated confidence radius, then the approximate gradients are accepted. Otherwise, the exact gradients are used such as analytical or finite differenced gradients. This hybrid design sensitivity analysis method is embedded in an in-house ALM based dynamic response optimizer, which solves three typical dynamic response optimization problems and one practical design problem for a tracked vehicle suspension system. The optimization results are compared with those of the conventional method that uses only exact gradients throughout optimization process. These comparisons show that the hybrid method is more efficient than the conventional method. Especially, in the tracked vehicle suspension system design, the proposed method yields 14 percent reduction of the total CPU time and the number of analyses than the conventional method, while giving similar optimum values.     

A new penalty parameter update rule in the augmented lagrange multiplier method for dynamic response optimization

Based on the value of the Lagrange multiplier and the degree of constraint activeness, a new update rule is proposed for penalty parameters of the ALM method. The theoretical exposition of this suggested update rule is presented by using the algorithmic interpretation and the geometric interpretation of the augmented Lagrangian. This interpretation shows that the penalty parameters can effect the performance of the ALM method. Also, it offers a lower limit on the penalty parameters that makes the augmented Lagrangian to be bounded. This lower limit forms the backbone of the proposed update rule. To investigate the numerical performance of the update rule, it is embedded in our ALM based dynamic response optimizer, and the optimizer is applied to solve six typical dynamic response optimization problems. Our optimization results are compared with those obtained by employing three conventional update rules used in the literature, which shows that the suggested update rule is more efficient and more stable than the conventional ones.     

Nanotentacle‐Structured Magnetic Particles for Efficient Capture of Circulating Tumor Cells

Circulating tumor cells (CTCs) have attracted considerable attention as promising markers for diagnosing and monitoring the cancer status. Despite many technological advances in isolating CTCs, the capture efficiency and purity still remain challenges that limit clinical practice. Here, the construction of “nanotentacle”‐structured magnetic particles using M13‐bacteriophage and their application for the efficient capturing of CTCs is demonstrated. The M13‐bacteriophage to magnetic particles followed by modification with PEG is conjugated, and further tethered monoclonal antibodies against the epidermal receptor 2 (HER2). The use of nanotentacle‐structured magnetic particles results in a high capture purity (>45%) and efficiency (>90%), even for a smaller number of cancer cells (≈25 cells) in whole blood. Furthermore, the cancer cells captured are shown to maintain a viability of greater than 84%. The approach can be effectively used for capturing CTCs with high efficiency and purity for the diagnosis and monitoring of cancer status.     

Performance analysis of fault-tolerant systems in parallelexecution of conversations

The execution overhead inherent in the conversation scheme, which is a scheme for realizing fault-tolerant cooperating processes free of the domino effect, is analyzed. Multiprocessor multicomputer systems capable of parallel execution of conversation components are considered and a queuing network model of such systems is adopted. Based on the queuing model, various performance indicators, including system throughput, average number of processors idling inside a conversation due to the synchronization required, and average time spent in the conversation, have been evaluated numerically for several application environments. The numeric results are discussed and several essential performance characteristics of the conversation scheme are derived. For example, when the number of participant processes is not large, say less than six, the system performance is highly affected by the synchronization required on the processes in a conversation, and not so much by the probability of acceptance-test failure     

Conservative quadratic RSM combined with incomplete small composite design and conservative least squares fitting

A new quadratic response surface modeling method is presented. In this method, the incomplete small composite design (ISCD) is newly proposed to reduce the number of experimental runs than that of the SCD. Unlike the SCD, the proposed ISCD always gives a unique design assessed on the number of factors, although it may induce the rank-deficiency in the normal equation. Thus, the singular value decomposition (SVD) is employed to solve the normal equation. Then, the duality theory is used to newly develop the conservative least squares fitting (CONFIT) method. This can directly control the over- or the under-estimation behavior of the approximate functions. Finally, the performance of CONFIT is numerically shown by comparing its’ conservativeness with that of conventional fitting method. Also, optimizing one practical design problem numerically shows the effectiveness of the sequential approximate optimization (SAO) combined with the proposed ISCD and CONFIT.     

Preparation and in Vivo Evaluation of a Dutasteride-Loaded Solid-Supersaturatable Self-Microemulsifying Drug Delivery System

The purpose of this study was to prepare a dutasteride-loaded solid-supersaturatable self-microemulsifying drug delivery system (SMEDDS) using hydrophilic additives with high oral bioavailability, and to determine if there was a correlation between the in vitro dissolution data and the in vivo pharmacokinetic parameters of this delivery system in rats. A dutasteride-loaded solid-supersaturatable SMEDDS was generated by adsorption of liquid SMEDDS onto Aerosil 200 colloidal silica using a spray drying process. The dissolution and oral absorption of dutasteride from solid SMEDDS significantly increased after the addition of hydroxypropylmethyl cellulose (HPMC) or Soluplus. Solid SMEDDS/Aerosil 200/Soluplus microparticles had higher oral bioavailability with 6.8- and 5.0-fold higher peak plasma concentration (C_max) and area under the concentration-time curve (AUC) values, respectively, than that of the equivalent physical mixture. A linear correlation between in vitro dissolution efficiency and in vivo pharmacokinetic parameters was demonstrated for both AUC and C_max values. Therefore, the preparation of a solid-supersaturatable SMEDDS with HPMC or Soluplus could be a promising formulation strategy to develop novel solid dosage forms of dutasteride.