Goodness-of-Fit Test for Large Number of Small Data Sets

A goodness-of-fit (gof) problem, i.e., testing whether observed data come from a specific distribution is one of the important problems in statistics, and various tests for checking distributional assumptions have been suggested. Most tests are for one data set with a large enough sample sizes. However, this research focuses on the gof problem when there are a large number of small data sets. In other words, we assume that the number of data sets p increases to infinity and the sample size of each small data set n is finite. In this dissertation, we will denote p and n as the number of data sets and the sample sizes of each data sets, respectively. Since the primary interest of this dissertation is testing whether every small data set comes from a known parametric family of distributions with different parameters, it is important to choose a gof test invariant to parameters of unknown distribution. Hence, as a basic approach, we suggest applying empirical distribution function (edf) based gof tests to every small data set and then combining P-values to obtain a single test. Two P-value combining methods, moment based tests and smoothing based tests, are suggested and their pros and cons are discussed. Especially, the two moment based tests, Edgington's method and Fisher's method, are compared with respect to Pitman efficiency and asymptotic power. We also find conditions that guarantee that the asymptotic null distribution of moment based tests based on empirical P-values is the same as that based on exact P-values. When the null is a location and scale family, there is no difficulty in applying the suggested test procedures. However, when the null is not a location and scale family, edf-based tests may depend on unknown parameters. To handle such a problem, we suggest using unconditional P-values and this requires an additional step of estimating the distribution of unknown parameters. Several issues related to estimating the distribution of unknown parameters and obtaining unconditional P-values are also discussed. The performance of suggested test procedures are investigated via simulations and these procedures are applied to microarray data

Piezoresistive tactile sensor discriminating multidirectional forces

Flexible tactile sensors capable of detecting the magnitude and direction of the applied force together are of great interest for application in human-interactive robots, prosthetics, and bionic arms/feet. Human skin contains excellent tactile sensing elements, mechanoreceptors, which detect their assigned tactile stimuli and transduce them into electrical signals. The transduced signals are transmitted through separated nerve fibers to the central nerve system without complicated signal processing. Inspired by the function and organization of human skin, we present a piezoresistive type tactile sensor capable of discriminating the direction and magnitude of stimulations without further signal processing. Our tactile sensor is based on a flexible core and four sidewall structures of elastomer, where highly sensitive interlocking piezoresistive type sensing elements are embedded. We demonstrate the discriminating normal pressure and shear force simultaneously without interference between the applied forces. The developed sensor can detect down to 128 Pa in normal pressure and 0.08 N in shear force, respectively. The developed sensor can be applied in the prosthetic arms requiring the restoration of tactile sensation to discriminate the feeling of normal and shear force like human skin.open0

Flying Cross-Border To Entrepreneurs: Business Angels In Croatia And Slovenia

The signifi cant expansion of business formation is playing a key role in the transformation of transitional economies. As a result of this and, the development of more entrepreneurial business culture, the role of endogenous venture capital, equity market provision, and the potential for business angels involvement is also growing. Despite these entrepreneurially driven developments, and the encouragement of individuals to establish new businesses, start-up companies in Croatia and Slovenia, they are facing the immediate issue of raising capital. Th is paper undertakes a comparative analysis of business angels in Croatia and Slovenia as part of they represent a key part of the response and solution to this problem. Their primary motivation is capital growth, and they seek to fi ll an equity gap and compensate for failures in the venture capital market wherever they appear. Th e study documents the current state of business angel activity and networking within the private equity market in Croatia and Slovenia, based on interviews and case studies. Th erefore, it informs the analysis of key functions that business angels can play in addressing problems faced by new small businesses in an emergent economic and investment environment

Self-Assembled Monolayers Coated Porous SnO2 Film Gas Sensor with Reduced Humidity Influence

Metal-oxide sensors, detect gas through the reaction of surface oxygen molecules with target gases, are promising for the detection of toxic pollutant gases, combustible gases, and organic vapors; however, their sensitivity, selectivity, and long-term stability limit practical applications. Porous structure for increasing surface area, adding catalyst, and altering the operation temperature are proposed for enhancing the sensitivity and selectivity. Although humidity can significantly affect the property and stability of the sensors, studies focusing on the long-term stability of gas sensors are scarce. To reduce the effects of humidity, 1H, 1H, 2H, 2H–perfluorooctyltriethoxysilane (PFOTS) was coated on a porous SnO2 film. The interconnected SnO2 nanowires improved the high surface area, and the PFOTS coating provided superhydrophobicity at water contact angle of 159°and perfect water vapor repellency inside E-SEM. The superhydrophobic porous morphology was maintained under relative humidity of 99% and operating temperature of 300 °C. The CO gas sensing of 5, 20, and 50 ppm were obtained with linearity at various humidity. Flame detection was also achieved with practical high humidity conditions. These results suggest the simple way for reliable sensing of nanostructured metal-oxide gas sensors with high sensitivity and long-term stability even in highly humid environments

Self-Assembled Monolayers Coated Porous SnO₂ Film Gas Sensor with Reduced Humidity Influence

Metal-oxide sensors, detect gas through the reaction of surface oxygen molecules with target gases, are promising for the detection of toxic pollutant gases, combustible gases, and organic vapors; however, their sensitivity, selectivity, and long-term stability limit practical applications. Porous structure for increasing surface area, adding catalyst, and altering the operation temperature are proposed for enhancing the sensitivity and selectivity. Although humidity can significantly affect the property and stability of the sensors, studies focusing on the long-term stability of gas sensors are scarce. To reduce the effects of humidity, 1H, 1H, 2H, 2H–perfluorooctyltriethoxysilane (PFOTS) was coated on a porous SnO2 film. The interconnected SnO2 nanowires improved the high surface area, and the PFOTS coating provided superhydrophobicity at water contact angle of 159°and perfect water vapor repellency inside E-SEM. The superhydrophobic porous morphology was maintained under relative humidity of 99% and operating temperature of 300 °C. The CO gas sensing of 5, 20, and 50 ppm were obtained with linearity at various humidity. Flame detection was also achieved with practical high humidity conditions. These results suggest the simple way for reliable sensing of nanostructured metal-oxide gas sensors with high sensitivity and long-term stability even in highly humid environments

Water harvest via dewing

Harvesting water from humid air via dewing can provide a viable solution to a water shortage problem where liquid-phase water is not available. Here we experimentally quantify the effects of wettability and geometry of the condensation substrate on the water harvest efficiency. Uniformly hydrophilic surfaces are found to exhibit higher rates of water condensation and collection than surfaces with lower wettability. This is in contrast to a fog basking method where the most efficient surface consists of hydrophilic islands surrounded by hydrophobic background. A thin drainage path in the lower portion of the condensation substrate is revealed to greatly enhance the water collection efficiency. The optimal surface conditions found in this work can be used to design a practical device that harvests water as its biological counterpart, a green tree frog, Litoria caerulea, does during the dry season in tropical northern Australia.11Nsciescopu

Tactile-direction-sensitive and stretchable electronic skins based on human-skin-inspired interlocked microstructures

Stretchable electronic skins with multidirectional force-sensing capabilities are of great importance in robotics, prosthetics, and rehabilitation devices. Inspired by the interlocked microstructures found in epidermal-dermal ridges in human skin, piezoresistive interlocked microdome arrays are employed for stress-direction-sensitive, stretchable electronic skins. Here we show that these arrays possess highly sensitive detection capability of various mechanical stimuli including normal, shear, stretching, bending, and twisting forces. Furthermore, the unique geometry of interlocked microdome arrays enables the differentiation of various mechanical stimuli because the arrays exhibit different levels of deformation depending on the direction of applied forces, thus providing different sensory output patterns. In addition, we show that the electronic skins attached on human skin in the arm and wrist areas are able to distinguish various mechanical stimuli applied in different directions and can selectively monitor different intensities and directions of air flows and vibrations.close8

Moth-Eye Mimicking Triboelectric Nanogenerator for Hybrid Energy Harvesting

1

나방 눈 구조를 모사한 접촉대전 나노발전기 개발

2