A new multi-mode multi-input–multi-output (MIMO) converter in an efficient low-voltage energy harvesting system for a gas sensor

Microsystem Technologies - This paper presents a new multi-mode multi-input–multi-output (MIMO) converter with a battery for operating an energy harvesting (EH) system for gas sensors. In...     

SYNCHRONIZATION OF CHAOTIC GYRO SYSTEMS USING RECURRENT WAVELET CMAC

This study addresses synchronization of two chaotic gyros by using an adaptive recurrent wavelet cerebellar model articulation controller (RWCMAC). The proposed adaptive RWCMAC system contains an RWCMAC and a robust controller. Based on Lyapunov stability theory, the parameters of RWCMAC are on-line tuned and the robust controller is designed for achieving H ^∞ robust performance. Finally, the proposed adaptive RWCMAC system is applied to synchronize two chaotic gyros. Numerical simulation results demonstrate the effectiveness of the proposed control scheme.     

Searching for optimal sensitivity of single-mode D-type optical fiber sensor in the phase measurement

To improve the sensitivity of a single-mode D-type optical fiber sensor, we selected a D-type optical fiber sensor with 4 mm long and 4 μm core thickness made of a single-mode fiber, a Au-coating on the sensor with a thickness range of 15–32 nm, a light wavelength of 632.8 nm, and an incident angle of 86.5–89.5° for different refractive index (1.33–1.40) sensing. These simulations are based on the surface plasmon resonance (SPR) theory using the phase method which shows that the sensitivity is proportional to the refractive index, Au film thickness and lower incident angle on the sensing interface. The sensitivity is higher than 4000 (degree/RIU), and the resolution is better than 2.5 × 10⁻⁶(RIU) as the minimum phase variation is 0.01°. This device is used to detect the refractive index or gas or liquid concentration in real-time. The proposed sensor is small, simple, inexpensive, and provides an in vivo test.     

Immobilization-free sequence-specific electrochemical detection of DNA using ferrocene-labeled peptide nucleic acid

An electrochemical method for sequence-specific detection of DNA without solid-phase probe immobilization is reported. This detection scheme starts with a solution-phase hybridization of ferrocene-labeled peptide nucleic acid (Fc-PNA) and its complementary DNA (cDNA) sequence, followed by the electrochemical transduction of Fc-PNA-DNA hybrid on indium tin oxide (ITO)-based substrates. On the bare ITO electrode, the negatively charged Fc-PNA-DNA hybrid exhibits a much reduced electrochemical signal than that of the neutral-charge Fc-PNA. This is attributed to the electrostatic repulsion between the negatively charged ITO surface and the negatively charged DNA, hindering the access of Fc-PNA-DNA to the electrode. On the contrary, when the transduction measurement is done on the ITO electrode coated with a positively charged poly(allylamine hydrochloride) (PAH) layer, the electrostatic attraction between the (+) PAH surface and the (-) Fc-PNA-DNA hybrid leads to a much higher electrochemical signal than that of the Fc-PNA. The measured electrochemical signal is proportional to the amount of cDNA present. In terms of detection sensitivity, the PAH-modified ITO platform was found to be more sensitive (with a detection limit of 40 fmol) than the bare ITO counterpart (with a detection limit of 500 fmol). At elevated temperatures, this method was able to distinguish fully matched target DNA from DNA with partial mismatches. Unpurified PCR amplicons were detected using a similar format with a detection limit down to 4.17 amol. This detection method holds great promise for single-base mismatch detection as well as electrochemistry-based detection of post-PCR products.     

Dendritic Pt shells coated on concave Pd nanocrystals: synthesis and use as electrocatalysts for acidic oxygen reduction reaction

A simple method to prepare a dendritic Pt-shell coating on concave Pd nanoparticles (NPs) was successfully developed. In this study, tuning the Pt precursor concentration in the reaction mixture allowed control over the length of the outer Pt dendrites, enclosed by (211) high-index facets or (110) facets were performed. The concave Pd NPs covered by short Pt dendrites (Pd/S-Pt) and long Pt dendrites (Pd/L-Pt) were applied as catalysts for the oxygen reduction reaction (ORR) in 0.1 M HClO₄ electrolyte solution. Pd/S-Pt with (211) facets had higher specific activity (0.106 mA cm^?2) than that of Pd/L-Pt with (110) facets (0.066 mA cm^?2) or commercial Pt/C (0.076 mA cm^?2). Additionally, the accelerated durability test (ADT) results revealed that the decay for the ORR kinetic current catalysed by Pd/S-Pt was 28.21%, which was smaller than that of Pt/C (58.15%). Thus, Pd/S-Pt was effective for catalysis of the ORR.     

Thermal-fluid characteristics of plate-fin heat sinks cooled by impingement jet

This work experimentally and numerically studies the thermal-fluid characteristics of plate-fin heat sinks under impingement cooling by adjusting the impinging Reynolds number, the impingement distance, and the fin dimensions. The parameters and the ranges under consideration are the impinging Reynolds number (Re = 5000–25,000), the impingement distance (Y/D = 4–28), the fin width (W/L = 0.08125–0.15625) and the fin height (H/L = 0.375–0.625). The results show that the heat transferred by the heat sink increases with the impinging Reynolds number. The thermal performance can be improved significantly even at low impinging Reynolds number. However, the improvement becomes indistinct as the impinging Reynolds number increases. The thermal resistance declines as the impingement distance increases, and is minimal at Y/D = 20 for various impinging Reynolds numbers. Additionally, the thermal resistance increases as the impingement distance increases further. Increasing the fin width can effectively reduce the thermal resistance. However, as the fin width increases beyond a particular value, the thermal resistance increases dramatically. Reducing the thermal resistance by increasing the fin height depends on a suitable impinging Reynolds number and fin width. Therefore, the effect of the fin height is weaker than that of the impinging Reynolds number or the fin width.     

自复位摇晃式支座运用于建筑隔震之可行性研究

运用摇晃（Rocking）及滚动（Rolling）机制研发了一种新型隔震支座,称作自复位摇晃式隔震支座（Self-centering Rocking Bearing,简称SCRB）,根据该支座力与位移关系,建立了以其作为隔震组件之隔震建筑理论运动模型;并以其滚动曲面半径、高宽比（Aspect Ratio）及上部结构自振周期作为研究参数,对SCRB隔震结构受自由振动、简谐力、地震地表加速度扰动进行数值分析。结果显示,经适当设计之SCRB隔震结构不具固定振动周期,不会被特定之扰动频率锁定而引发共振;在受大地震时,能有效降低上部结构之加速度反应,亦能减少层间变位（Drift）,可用于建筑隔震。     

Thermal performance of plate-fin vapor chamber heat sinks

Since vapor chambers exhibit excellent thermal performance, they are suited to use as bases of heat sinks. This work experimentally studies the thermal performance of plate-fin vapor chamber heat sinks using infrared thermography. The effects of the width, height and number of fins and of the Reynolds number on the thermal performance are considered. Experimental data are compared with corresponding data for conventional aluminum heat sinks. The results show that generated heat is transferred more uniformly to the base plate by a vapor chamber heat sink than by a similar aluminum heat sink. Therefore, the maximum temperature is effectively reduced. The overall thermal resistance of the vapor chamber heat sink declines as the Reynolds number increases, but the strength of the effect falls. The effect of the fin dimensions on the thermal performance is stronger at a lower Reynolds number. At a low Reynolds number, a suitable number of fins must be chosen to ensure favorable thermal performance of the vapor chamber heat sink. However, at a high Reynolds number, the thermal performance improves as the fin number increases.     

A novel approach for measuring the maximum process-loss information in multiple production line conditions

The process-loss index L_e , the expected value of the ratio of the quadratic loss function to the square value of half specification width, proposed by Johnson (1992 Johnson, T. 1992. The relationship of C_pm to squared error loss. Journal of Quality Technology, 24(4): 211–215. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar], The relationship of C_pm to squared error loss. Journal of Quality Technology, 24 (4), 211–215), has been widely used in a variety of industries to provide a numerical loss measure for assessing the performance of their production processes. However, the sampling distribution of its uniformly minimum variance unbiased estimator (UMVUE), obtained from traditional approaches involving unknown parameters, is able neither to form classical confidence intervals (CCIs) nor to provide justifiable process-loss information in practice. To tackle this disadvantage, in this paper a novel approach known as generalised confidence intervals (GCIs) is adopted. Instead of Monte Carlo simulations that were popularly utilised in implementing the GCIs method for assessing production process performance, we theoretically derive analytical forms of upper confidence bounds (L _e -GUCB) for L _e and program them to provide the maximum process-loss information for the manufacturing processes. Two common manufacturing scenarios are presented in order to work out: (1) whether the underlying production process loss is capable (or whether products received from one supplier are acceptable); and (2) whether the maximum process-loss information existing in multiple production line conditions is acceptable (or whether products received from several suppliers are acceptable). The applicability of the results is demonstrated by two examples.     

The effect of fiber angle on the natural frequencies of orthotropic composite pre-twisted blades

The eigenvalue problem of a tapered pre-twisted orthotropic composite blade is formulated by employing the differential quadrature method (DQM). The Euler–Bernoulli beam model is used to characterize the pre-twisted orthotropic composite blade. The Kelvin–Voigt internal and linear external damping coefficients are employed and determined for the orthotropic composite blade. The DQM is used to transform the partial differential equations of a tapered pre-twisted orthotropic composite blade into a discrete eigenvalue problem. The Chebyshev–Gauss–Lobatto sample point equation is used to select the sample points. In this study, the effects of the fiber orientation, internal damping, external damping, inclined angle and the rotation speed on the natural frequencies for a tapered pre-twisted orthotropic composite blade are investigated. The effect of the number of sample points on the accuracy of the calculated natural frequencies is also discussed. The integrity and computational efficiency of the DQM in this problem will be demonstrated through a number of case studies. Numerical results indicated that the DQM is valid and efficient for a pre-twisted orthotropic composite blade formulation.