Formal approach to scenario analysis

Scenarios offer promise as a way to tame requirements analysis, but progress has been impeded by the lack of a systematic way to analyze, generate, and validate them. The authors propose such a method and apply it to a simple PBX system. Their method has a formal mathematical base, generates precise scenarios, accommodates change, and keeps users involved in the process     

Changes of sex hormone levels in patients with hepatitis B virus-related postnecrotic cirrhosis: relationship to the severity of portal hypertension

The purpose of this study was to develop a model in which the regional pharmacokinetics of a drug in tumor and nontumorous tissue could be evaluated under a variety of physiological conditions. To this effect, the growth of a human choriocarcinoma cell line (JAR) was evaluated in pigs immunosuppressed with 25 mg cyclosporine/kg every 24 h. During an initial study, we demonstrated that suspensions containing approximately 3 million JAR cells with and without 1 million normal human fibroblasts injected s.c. into the inguinal region of pigs resulted in the growth of tumors consisting primarily of polygonal neoplastic cells. Multinucleate tumor cells, inflammatory cells, necrotic debris, and vascular endothelial cells were also present. Maximal tumor size was noted on day 12, after which time tumor regression occurred. The coinoculation of fibroblasts resulted in significantly larger tumors. Two single pedicle, axial pattern tubed flaps were created in the inguinal area of 4 pigs. JAR cells and fibroblasts were transplanted to one flap to allow for tumor formation. The other flap served as a nontumorous control. Both flaps were removed for perfusion with a physiological solution 11 days later. Glucose utilization, lactate concentrations, lactate dehydrogenase activities, and microscopic evaluation of skin samples were used to assess flap viability. All flaps remained viable for 8 h of perfusion. The only differences detected between nontumorous and tumor flaps was the initial perfusion pressure which was significantly lower in tumor flaps (P < 0.05). The isolated perfused tumor and skin flap is unique in that it consists of a tumor surrounded by normal tissue with an intact microvascular system and can be utilized to design regional pharmacokinetic studies describing drug distribution in tumor tissue.     

Bidirectional Reflectometry. Part I.: A High Resolution Laser Bidirectional Reflectometer With Results on Several Optical Coatings

A laser-source bidirectional reflectometer that is fully automated and has angular resolution on the order of one degree has been designed and built. The direction of incidence and viewing can be independently varied over an entire hemisphere except for directions more than 77.5° from the normal, and the two directions must be at least 2.5° apart. Bidirectional reflectances for 15 samples of black and white coatings are presented.     

Marker automata

This paper deals with finite automata augmented with markers which the automata can move about on their input tapes. The concept of augmenting markers to automata was first introduced by Blum and Hewitt [1] in two-dimensional automata. Kreider, Ritchie, and Springsteel [6, 7, 8, 12] investigated recognition of context-free languages by (one-dimensional) automata with markers. In this paper, we investigate some fundamental properties of marker automata and study their relationships to other types of automata and languages. The main result in this paper is the establishment of an infinite hierarchy of languages recognizable by deterministic and deterministic, halting marker automata. It also turns out that, because of the equivalence of finite marker automata and multi-head automata, the study of three-marker automata becomes very interesting due to results of Hartmanis [4] and Savitch [10].     

Numerical simulation of semi-crystalline nylon 6: elastic constants of crystalline and amorphous parts

The elastic responses of crystalline and amorphous parts in semi-crystalline nylon 6 have been determined by computer simulation using the finite element method. Semi-crystalline nylon 6 has been modelled as a composite consisting of alternating layers of lamellar crystals and amorphous regions. Full morphological details identified previously by Lin and Argon in highly textured nylon 6 bulk samples have been incorporated in the model. An optimization scheme has been employed to search systematically for the individual components' elastic constants which give rise to a composite elastic behaviour as that measured by Lin and Argon. A two-dimensional plane strain finite element analysis has been performed to evaluate the composite elastic behaviour for a given set of constituents' elastic constants. The resulting elastic constants of semi-crystalline nylon 6 for the optimized values of crystalline and amorphous elastic properties were within 6% average error with the experimental data. The computations also revealed that a high stress concentration exists in the crystalline region. Therefore, experimental measurements of plastic resistance may represent a significant underestimate of the intrinsic critical resolved shear strength of polymer crystals.     

High-Efficiency WCDMA Envelope Tracking Base-Station Amplifier Implemented With GaAs HVHBTs

A record high-performance GaAs high-voltage HBT (HVHBT)-based WCDMA base-station power amplifier is presented, which uses an envelope tracking bias system to achieve high efficiency and linearity. A wideband envelope amplifier provides dynamic collector supply biasing to the RF stage. A digital pre-distortion technique is employed to satisfy the linearity specifications of WCDMA. The measured overall power-added efficiency reached 58% with a normalized root-mean-square (RMS) error of 2.9% and an adjacent channel leakage ratio (ACLR) of -49 dBc at 5-MHz offset at an average output power of 42 W and a gain of 10.3 dB for a single carrier WCDMA signal with 6.6-dB peak-to-average power ratio. A memory mitigation algorithm further improves the linearity, resulting in an ACLR of -70 dBc and a normalized RMS error of 0.3%. Measurements were made to quantify separately the efficiency contributions of the HVHBT-based RF stage, and of the envelope amplifier. The measurements show that the RF stage operates at collector efficiency above 85% over most of the instantaneous power range of the WCDMA signal. This remarkably high efficiency is the result of low ldquoon-resistancerdquo and low (and nearly voltage independent) output capacitance of the HVHBT.     

High-performance active polyphase filter design for digital TV tuner

This paper presents the polyphase filter design for the tuner of DTV front-end system. The polyphase filter is designed with an active circuit to improve the chip performance. Most of passive capacitor and resistor components are replaced with MOS transistors. The proposed method not only can reduce the chip area but also gain the signal level. For the prototyping implementation, the current channel bands in Taiwan are referred, which the frequency range is from 530 to 602 MHz for DTV programs. In experiments, the polyphase filter can achieve 85 dB for the image rejection in the center frequency. The main signal can be gained about 2-5 dB without using extra amplifier. The chip size is about 0.09 mm², and the average power dissipation is about 15 mW, when the chip technology employed TSMC 0.35 μm CMOS process. The proposed chip outperforms with less area and higher gain.     

Software Optimization in Ultrasound Imaging Technique Using Improved Deep Belief Learning Network on the Internet of Medical Things Platform

Wireless Personal Communications - The Internet of Medical&nbsp;Things (IoMT) is the array of medical instruments and related technologies that link Information Technology (IT) systems in...     

Torsional Energy Barriers in Dimethyl Ether and Perfluoro-Dimethyl Ether: Electronic Structure Contributions

The optimized geometries, torsional energy barriers and atomic charge in dimethyl ether and perfluoro-dimethyl ether have been investigated with density functional theory (dft) molecular orbital calculations. The optimized dimethyl ether (DME) and perfluoro-dimethyl ether (PFDME) geometries have been obtained and are in good agreement with experimental results. The torsional energy barriers for both the DME and PFDME have been calculated by incrementally increasing the dihedral angle and performing a full-geometry optimization. The DME and PFDME barriers have been compared, and the geometries of the transition states for both molecules are given. The net atomic charges of both the optimized and transition state species are calculated for both DME and PFDME and shown to be consistent with a stereoelectronic effect (anomeric) that mixes an anti-bonding C–H-centered molecular orbital and an oxygen lone pair. The effects of this antiperiplanar electronic interaction are discussed, and the calculated torsion energy barriers are justified using a simplified second-order bonding model.     

Kirigami‐Inspired Self‐Assembly of 3D Structures

Self‐assembly of 3D structures presents an attractive and scalable route to realize reconfigurable and functionally capable mesoscale devices without human intervention. A common approach for achieving this is to utilize stimuli‐responsive folding of hinged structures, which requires the integration of different materials and/or geometric arrangements along the hinges. It is demonstrated that the inclusion of Kirigami cuts in planar, hingeless bilayer thin sheets can be used to produce complex 3D shapes in an on‐demand manner. Nonlinear finite element models are developed to elucidate the mechanics of shape morphing in bilayer thin sheets and verify the predictions through swelling experiments of planar, millimeter‐scaled PDMS (polydimethylsiloxane) bilayers in organic solvents. Building upon the mechanistic understandings, The transformation of Kirigami‐cut simple bilayers into 3D shapes such as letters from the Roman alphabet (to make “ADVANCED FUNCTIONAL MATERIALS”) and open/closed polyhedral architectures is experimentally demonstrated. A possible application of the bilayers as tether‐less optical metamaterials with dynamically tunable light transmission and reflection behaviors is also shown. As the proposed mechanistic design principles could be applied to a variety of materials, this research broadly contributes toward the development of smart, tetherless, and reconfigurable multifunctional systems.