An evolutionary testbed for software technology evaluation

Empirical evidence and technology evaluation are needed to close the gap between the state of the art and the state of the practice in software engineering. However, there are difficulties associated with evaluating technologies based on empirical evidence: insufficient specification of context variables, cost of experimentation, and risks associated with trying out new technologies. In this paper, we propose the idea of an evolutionary testbed for addressing these problems. We demonstrate the utility of the testbed in empirical studies involving two different research technologies applied to the testbed, as well as the results of these studies. The work is part of NASAs High Dependability Computing Project (HDCP), in which we are evaluating a wide range of new technologies for improving the dependability of NASA mission-critical systems.     

Developing model-based software to optimise wheat storage and transportation: A real-world application

This paper investigates a real-world case of a logistical management problem. We determine the optimal amounts of wheat to be transported from each producing province to each consuming province per month across the year. The problem was formulated as a linear integer programming (LIP) model, which could then be solved using LINGO optimisation software. As the LIP model needs to be run each month, a genetic algorithm (GA) was developed to solve the real-size problems in a reasonable time period. The solutions obtained by LINGO are compared with those obtained from the GA and the results show that the developed GA is efficient in terms of computational time and the quality of the solutions obtained.     

A low-power reduced swing global clocking methodology

In this brief, we investigate the potential of reduced swing clock networks for low-power applications. We designed and laid out a full swing conventional and a reduced swing H-tree clock distribution network in 0.13-/spl mu/m CMOS technology operating at 500 MHz. In the reduced swing clock network, the swing was reduced in the global clock distribution network and was restored to the full swing in the local clock distribution domains. The post-layout simulation results of this research shows that a power saving of 22% under nominal operating condition is feasible.     

Solid-state supercapacitor based on breath figured polymethyl methacrylate deposited by graphene: the effect of electrode surface

Solid-state supercapacitors are fabricated using transparent polymethyl methacrylate (PMMA) films decorated by breath figures BF, as an electrode and polyvinyl alcohol (PVA)-H₂SO₄ as an electrolyte. The holes on the surface of the transparent PMMA created by BF method have diameters of 0.5–10 μm. Graphene is deposited by spray coating using a dispersion mixture of graphene layers. The fabricated electrodes were characterized by cyclic voltammetry (CV), galvanostatic charge–discharge, electrochemical impedance spectroscopy, charge stability and life time for evaluating their supercapacitance performance. From CV data at 5 mV/s scan rate, high specific capacitance equal to 344 for BFPMMA/G F/g and, 45 F/g for PMMA/G has been measured. By the same way, energy densities have been measured as 430 and 56.25 Wh/kg for the mentioned electrodes, respectively.     

Modeling of Advanced High Strength Steels with the realistic microstructure–strength relationships

The objective of the work is to consider the first-order effects of the realistic microstructure morphology in the macroscale modeling of the multiphase Advanced High Strength Steels (AHSS). Instead of using constitutive equations at macroscale, the strength–microstructure relationship is studied in the forms of micromechanical and multiscale models that do not make considerable simplifications with regard to the microscale geometry and topology. The trade-off between the higher computational time and the higher accuracy has been offset with a stochastic approach in the construction of the microscale models. The multiphase composite effects of AHSS microstructure is considered in realistic microstructural models that are stochastically built from AHSS micrographs. Computational homogenization routines are used to couple micro and macroscale and resultant stress–strain relations are compared for models built with the simplified and idealized geometries of the microstructure. The results from this study show that using a realistic representation of the microstructure, either for DP or TRIP steel, could improve the accuracy of the predicted stress and strain distribution. The resultant globally averaged effective stress and strain fields from realistic microstructure model were able to accurately capture the onset of the plastic instability in the DP steel. It is shown that the macroscale mechanical behavior is directly affected by the level of complexities in the microscale models. Therefore, greater accuracy could be achieved if these stochastic realistic microstructures are used at the microscale models.     

A Robust Approach Toward Recognizing Valid Arterial-Blood-Pressure Pulses

We propose a projection method based on singular value decomposition (SVD) to validate arterial blood pressure (ABP) signal in order to avoid artifacts and noise in subsequent processing. The projection has been done on 567 validated ABP beats collected from 51 patients hospitalized in University of California, Los Angeles Medical Center. Then, we compare the performance of the proposed projection method with that of a previously developed algorithm, signal abnormality index (SAI), which is a value- and trend-based approach, and has shown to be effective in cleaning the ABP waveforms. The testing dataset consists of 1336 ten-second ABP segments (18 472 ABP beats) of both valid and invalid pulses selected randomly from multiparameter intelligent monitoring for intensive care II database. The proposed projection approach that validates the signal based on the shape of the waveform achieves a true positive rate (TPR) of 99.06%, 5.43% higher than that of the SAI, and a false positive rate (FPR) of 7.69%, 17.38% lower than that of SAI. Integration of some of the SAI-value-based abnormality conditions to the validation process of SVD-based method can further improve the performance by reducing the FPR to 3.92%, while keeping the TPR at the high rate of 99.05%.      

An Empirical Study of Collaborative Acoustic Source Localization

Field biologists use animal sounds to discover the presence of individuals and to study their behavior. Collecting bio-acoustic data has traditionally been a difficult and time-consuming process in which researchers use portable microphones to record sounds while taking notes of their own detailed observations. The recent development of new deployable acoustic sensor platforms presents opportunities to develop automated tools for bio-acoustic field research. In this work, we implement both two-dimensional (2D) and three-dimensional (3D) AML-based source localization algorithms. The 2D algorithm is used to localize marmot alarm-calls of marmots on the meadow ground. The 3D algorithm is used to localize the song of Acorn Woodpecker and Mexican Antthrush birds situated above the ground. We assess the performance of these techniques based on the results from four field experiments: two controlled test of direction-of-arrival (DOA) accuracy using a pre-recorded source signal for 2D and 3D analysis, an experiment to detect and localize actual animals in their habitat, with a comparison to ground truth gathered from human observations, and a controlled test of localization experiment using pre-recorded source to enable careful ground truth measurements. Although small arrays yield ambiguities from spatial aliasing of high frequency signals, we show that these ambiguities are readily eliminated by proper bearing crossings of the DOAs from several arrays. These results show that the AML source localization algorithm can be used to localize actual animals in their natural habitat using a platform that is practical to deploy.     

A highly linear wideband 0.3-to-2.7 GHz variable-gain amplifier

A design of a differential variable-gain amplifier (VGA) with high IP3 (third-order intercept point) is discussed. To improve IP3, the third-order intermodulation products, which are generated by both an intrinsic third-order nonlinearity and a second-order interaction of a transistor, are minimized by using a nonlinear conductance. Unlike prior methods, the proposed method enables the achievement of both constant and broadband IP3 for various VGA gain settings. A design example with virtual but realistic BSIM4 transistor models is discussed to verify the analysis. The resultant amplifier example was designed and simulated in a 28-nm FDSOI CMOS technology. The amplifier achieved more than 15 dBm input-referred IP3 across a 2.4-GHz bandwidth from 0.3-to-2.7 GHz with a variable gain of 0-to-8.5 dB while consuming 3.3 mA from a 1.5-V supply.