Modern development methods and tools for embedded reconfigurable systems: A survey

Heterogeneous reconfigurable systems provide drastically higher performance and lower power consumption than traditional CPU-centric systems. Moreover, they do it at much lower costs and shorter times to market than non-reconfigurable hardware solutions. They also provide the flexibility that is often required for the engineering of modern robust and adaptive systems. Due to their heterogeneity, flexibility and potential for highly optimized application-specific instantiation, reconfigurable systems are adequate for a very broad class of applications across different industry sectors. What prevents the reconfigurable system paradigm from a broad proliferation is the lack of adequate development methodologies and electronics design tools for this kind of systems. The ideal would be a seamless compilation of a high-level computation process specification into an optimized mixture of machine code executed on traditional CPU-centric processors and on the application-specific decentralized parallel data-flow-dominated reconfigurable processors and hardware accelerators. Although much research and development in this direction was recently performed, the adequate methodologies and tools necessary to implement this compilation process as an effective and efficient hardware/software co-synthesis flow are unfortunately not yet in place. This paper focuses on the recent developments and development trends in the design methods and synthesis tools for reconfigurable systems. Reconfigurable system synthesis performs two basic tasks: system structure construction and application process mapping on the structure. It is thus more complex than standard (multi-)processor-based system synthesis for software-programmable systems that only involves application mapping. The system structure construction may involve the macro-architecture synthesis, the micro-architecture synthesis, and the actual hardware synthesis. Also, the application process mapping can be more complicated and dynamic in reconfigurable systems. This paper reviews the recent methods and tools for the macro- and micro-architecture synthesis, and for the application mapping of reconfigurable systems. It puts much attention to the relevant and currently hot topic of (re-)configurable application-specific instruction set processors (ASIP) synthesis, and specifically, ASIP instruction set extension. It also discusses the methods and tools for reconfigurable systems involving CPU-centric processors collaborating with reconfigurable hardware sub-systems, for which the main problem is to decide which computation processes should be implemented in software and which in hardware, but the hardware/software partitioning has to account for the hardware sharing by different computation processes and for the reconfiguration processes. The reconfigurable system area is a very promising, but quite a new field, with many open research and development topics. The paper reviews some of the future trends in the reconfigurable system development methods and tools. Finally, the discussion of the paper is summarized and concluded.     

Glutathione Deficiency during Early Postnatal Development Causes Schizophrenia-Like Symptoms and a Reduction in BDNF Levels in the Cortex and Hippocampus of Adult Sprague–Dawley Rats

Growing body of evidence points to dysregulation of redox status in the brain as an important factor in the pathogenesis of schizophrenia. The aim of our study was to evaluate the effects of l-buthionine-(S,R)-sulfoximine (BSO), a glutathione (GSH) synthesis inhibitor, and 1-[2-Bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine dihydrochloride (GBR 12909), a dopamine reuptake inhibitor, given alone or in combination, to Sprague–Dawley pups during early postnatal development (p5–p16), on the time course of the onset of schizophrenia-like behaviors, and on the expression of brain-derived neurotrophic factor (BDNF) mRNA and its protein in the prefrontal cortex (PFC) and hippocampus (HIP) during adulthood. BSO administered alone decreased the levels of BDNF mRNA and its protein both in the PFC and HIP. Treatment with the combination of BSO + GBR 12909 also decreased BDNF mRNA and its protein in the PFC, but in the HIP, only the level of BDNF protein was decreased. Schizophrenia-like behaviors in rats were assessed at three time points of adolescence (p30, p42–p44, p60–p62) and in early adulthood (p90–p92) using the social interaction test, novel object recognition test, and open field test. Social and cognitive deficits first appeared in the middle adolescence stage and continued to occur into adulthood, both in rats treated with BSO alone or with the BSO + GBR 12909 combination. Behavior corresponding to positive symptoms in humans occurred in the middle adolescence period, only in rats treated with BSO + GBR 12909. Only in the latter group, amphetamine exacerbated the existing positive symptoms in adulthood. Our data show that rats receiving the BSO + GBR 12909 combination in the early postnatal life reproduced virtually all symptoms observed in patients with schizophrenia and, therefore, can be considered a valuable neurodevelopmental model of this disease.     

Mathematical Description of Experimentally Determined Charge Distributions of a Unipolar Diffusion Charger

The charge distributions of an improved opposed flow unipolar diffusion charger were measured using a tandem differential mobility analyzer (DMA) set up in a size range of approximately 20–400 nm. The charger is intended to be used in a portable aerosol sizer to measure particle size distributions. The determined charge distributions were represented by lognormal distributions, and a set of equations and coefficients was developed to calculate the charge distributions. These equations can be easily implemented in software for size distribution measurements. The agreement between the mathematically derived and measured charge distributions is very good, with regression coefficients R ² > 0.96. The investigations showed that approximately 55% of 20-nm particles remain uncharged, while up to 25 elementary charges need to be considered for multiple charge correction of 400-nm particles. Comparison with the Fuchs theory delivered satisfying agreement with the measured average charge levels, but charge distributions cannot be described by the Fuchs theory, likely caused by the charger geometry.

Copyright 2012 American Association for Aerosol Research     

Fractal aggregate model of chain with mixed statistics

A fractal aggregate model is presented for chain molecules which are described by different statistics on different length scales. It describes the macromolecular chains as aggregates composed either of non-porous monomers or thermal blobs. The mass of non-porous monomer and the thermal blob mass are both dependent on the solvent quality. The blob mass can be calculated knowing the non-porous monomer mass in a solvent under consideration and that at the theta condition. Both the quantities can be deduced from the solution properties. The values of thermal blob mass normalized by that of monomer, deduced from intrinsic viscosity data for several polymers, form a dependence on Mark-Houvink-Sakurada exponent. This dependence is confirmed by the solvent quality dependence of the polymer mass at the onset of excluded volume behavior and some values obtained from sedimentation coefficients.     

Pulmonary thromboembolism

Pulmonary embolism (PE) is a serious complication of chronic obstructive pulmonary disease (COPD). Retrospective studies on patients with COPD treated in the intensive care unit (ICU) were performed to determine: 1) the frequency of PE; 2) the clinical course of PE in cases of COPD in the ICU; and 3) the frequency of PE as a cause of death in the studied group. The frequency of PE was 10.9% in COPD patients. In the group analysed, clinical presentation of PE was characterized by acute severe, life-threatening complications leading to death in 86.7% of cases. PE was the most frequent cause of death (40.6%) in COPD patients in the ICU. The results of treatment of pulmonary embolism in chronic obstructive pulmonary disease are poor and mortality in this group of patients is very high. We believe that improvement of management can be achieved by antithromboembolic prophylaxis, which should be instituted as soon as possible in all patients with chronic obstructive pulmonary disease in the intensive care unit.     

Design of the synthesis of fine HA powder for suspension plasma spraying

Hydroxyapatite (HA, Ca₁₀(PO₄)₆(OH)₂) is a bioactive material being frequently used as a coating onto implants. The typical coating technology is air plasma spraying with the use of coarse powder. The resulting coatings are relatively thick (about 200-400 µm) and porous. Much thinner coatings being 5-40 µm thick, can be obtained by emerging technology of suspension plasma spraying with the use of powder particles having the diameters ranging from a few submicrometers to a few micrometers. The paper describes the way of synthesizing and preparing such fine powder starting from an aqueous solution of ammonium phosphate (H₂(PO₄)NH₄) and calcium nitrate (Ca(NO₃)·4H₂O) using statistical design of experiments (DOE). The design was made using composite matrix including a full factorial plan, star points and 3 experiments in the centre. The crystal phases purity and the mass of powder batch were the optimized responses of the powder synthesis and the concentration of calcium ions and volume of ammonium hydroxide were the experimental variables. The synthesized material was characterized by X-ray diffraction (XRD). The powder was calcined and crushed using a milling machine with zirconia balls and resulting morphology and size of fine particles was characterized using scanning electron microscope (SEM) and laser sizer correspondingly. The powder was then formulated into water and alcohol based suspension and the zeta potential was determined to understand its capacity of agglomeration. It was found out that the formulation of the suspension with the use of ethanol slightly favours dispersion of solid particles in the suspension. The initial tests of water based suspension plasma spraying onto titanium substrate were also carried out and the XRD phase analysis of obtained coatings was carried out the presence of HA and its phases of decomposition.     

Sol-Gel Glass-Encapsulated Crown Ethers for the Separation and Preconcentration of Strontium from Acidic Media

Extraction chromatography employing an inert polymeric support impregnated with a crown ether (typically, 4,4’,(5’)-di-(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6)), either neat (i.e., undiluted) or as a solution in 1-octanol, has previously been shown to provide an effective means for the isolation of radiostrontium from a variety of sample types for subsequent determination. In this study, sol-gel chemistry has been employed to prepare sorbents in which DtBuCH18C6 is encapsulated in a silica matrix. The resultant materials have been evaluated for their ability to retain strontium ion and compared to a commercially available extraction chromatographic (EXC) resin. Certain of the new materials are shown to provide uptake efficiencies comparable to those obtained with the commercial resins, although unless a porogen is employed, the kinetics of strontium uptake are significantly slower. In contrast to conventional EXC materials, however, strontium uptake by DtBuCH18C6-loaded glasses does not increase in proportion to the amount of extractant present, indicating that not all of the crown ether present is available for interaction with the metal ion.