POWER-Area-Performance Characteristics of FPGA-based Sigma-Delta FIR Filters

While one-bit ΣΔ modulators are widely used in Analog to Digital conversion stages due to their inherent linearity and precision, it is less common for the entire digital processing path to operate in single bit mode at the oversampled rate of the conversion system. The conventional approach has been to decimate the signal bit stream after conversion and for the remaining processing to be performed in standard multi-bit binary at the Nyquist rate and with a resolution mandated by the dynamic range and noise. Using a Finite Impulse Response filter design as an example, we compare the area and performance of this conventional approach with the alternative single bit approach that operates directly on the ΣΔ data stream using ternary coefficients {?1, 0, +1} derived from the ΣΔ modulation of the target impulse response. Filters exhibiting approximately equivalent spectral performance in the two alternative approaches were developed using VHDL and simulated using some commercial FPGA types. In these experiments, the single-bit filters using ternary coefficients were found to dissipate less power compared to the conventional approach despite their need to operate at much higher clock rates. They also exhibit up to 40% higher performance and offer useful area savings at lower filter orders. At higher orders, the ΣΔ approach retains its power and performance advantages but exhibits slightly higher chip area. The simplicity and low power of the ΣΔ approach makes it applicable to mobile communication processing using low cost FPGA technology.     

Review of convective heat transfer enhancement with nanofluids

Nanofluids are considered to offer important advantages over conventional heat transfer fluids. Over a decade ago, researchers focused on measuring and modeling the effective thermal conductivity and viscosity of nanofluids. Recently important theoretical and experimental research works on convective heat transfer appeared in the open literatures on the enhancement of heat transfer using suspensions of nanometer-sized solid particle materials, metallic or nonmetallic in base heat transfer fluids. The purpose of this review article is to summarize the important published articles on the enhancement of the forced convection heat transfer with nanofluids.     

Oxidation stability and compositional characteristics of oils from microwave roasted pumpkin seeds during thermal oxidation

The oxidative stability and compositional characteristics of the pumpkin seed oil (PSO) exposed to microwaves were studied during heating at 170°C. The oxidative indices such as free fatty acid (FFA), peroxide value (PV), p-anisidine value (p-AV), TOTOX, specific extinctions and thiobarbituric acid (TBA) value of oils were significantly increased, and the increments were found to be significantly higher (P < 0.05) in unroasted seed oil as compared to roasted seed oil. The relative contents of polyunsaturated fatty acids (PUFAs) were decreased to 84.7%, and saturated fatty acids (SFAs) were increased to 119.5% in unroasted sample, after 9 h of heating. On the other hand, in 12 min roasted samples, the relative contents of PUFAs were decreased to 97.0%, and SFAs were increased to 102.6% after 9 h of heating. The triacylglycerol species LLL and OLL levels were decreased as a consequence of increased heating time, and the reduction tended to be significantly higher in unroasted samples as compared to roasted ones. The oxidation products formed were also investigated by FTIR. The present results indicated that microwave roasting of pumpkin seeds markedly enhanced the oxidative stability of the oils during heating.     

Mechanical Control of Periodic Precipitation in Stretchable Gels to Retrieve Information on Elastic Deformation and for the Complex Patterning of Matter

Material design using nonequilibrium systems provides straightforward access to complexity levels that are possible through dynamic processes. Pattern formation through nonequilibrium processes and reaction–diffusion can be used to achieve this goal. Liesegang patterns (LPs) are a kind of periodic precipitation patterns formed through reaction–diffusion. So far, it has been shown that the periodic band structure of LPs and the geometry of the pattern can be controlled by experimental conditions and external fields (e.g., electrical or magnetic). However, there are no examples of these systems being used to retrieve information about the changes in the environment as they form, and there are no studies making use of these patterns for complex material preparation. This work shows the formation of LPs by a diffusion–precipitation reaction in a stretchable hydrogel and the control of the obtained patterns by the unprecedented and uncommon method of mechanical input. Additionally, how to use this protocol and how deviations from “LP behavior” of the patterns can be used to “write and store” information about the time, duration, extent, and direction of gel deformation are presented. Finally, an example of using complex patterning to deposit polypyrrole by using precipitation patterns is shown as a template.     

Evaluation of sequential thallium and gallium scans of the chest in AIDS patients

With decreasing incidence of pneumocystis carinii pneumonia (PCP) in AIDS as a result of prophylactic regimens, there is a higher incidence of tuberculosis (TB), mycobacterium avii complex (MAC), kaposi sarcoma and malignant lymphoma. There is a need for differentiating these various pathological entities. The purpose of this study was for a retrospective evaluation of sequential thallium and gallium scans in AIDS patients for differentiating intrathoracic kaposi sarcoma from malignant lymphoma and opportunistic infections. METHODS: A total of 181 patients had both studies completed between March 1992 and May 1994. The final diagnosis was verified only in 83 patients. Results were correlated with the CD4 counts, bronchoscopic and chest radiograph findings. RESULTS: In patients with pulmonary kaposi sarcoma and no opportunistic infections (19 patients), a thallium-positive, gallium-negative pattern was detected in 17 patients with a sensitivity of 89%. In the presence of kaposi sarcoma plus opportunistic infections, this pattern was only detected in 7 of 19 patients (sensitivity dropped to 37%). In 45 patients with opportunistic infections and no kaposi sarcoma, only two false-positive findings were found in patients with cytomegalic virus pneumonia for a specificity of 96%. For the whole group of 83 patients, sensitivity was 63%; specificity 95%; positive predictive value 92%; accuracy 81%; and negative predictive value 75%. CONCLUSION: A thallium-positive, gallium-negative pattern in AIDS patients has a high specificity for the diagnosis of kaposi sarcoma, however, the sensitivity dropped from 89% to 37% in the presence of opportunistic infections.     

An approach for determining surface temperature distributions of solid objects subjected to heating applications

This study presents a simple technique of determining surface temperature values and/or distributions of solid objects of various geometrical shapes (e.g. infinite slab, infinite cylinder, and sphere) during heating in a medium under natural or forced convection conditions. In the model, the boundary condition of the third kind (i.e., 0.1 < Bi < 100) in transient heat transfer, which is commonly encountered, is used. In many practical applications ranging from metallurgy to food engineering processes, the measurement of surface temperatures of such solid objects is a remarkable problem; however, centre temperature measurements are quite easy. For this reason, simple and accurate models are required for use in practice. The proposed model depends on the centre temperature and determines the surface temperatures using the centre temperature measurements. In order to test the present analytical model, an actual example for a slab object was given and the centre and surface temperature profiles were drawn. In addition, the centre and surface temperature distributions for infinite slab, infinite cylinder, and sphere were computed for the values of 0.1, 1, 10, and 100 of the Biot number and were exhibited as reference graphics. As a result, the present model is capable of determing surface temperatures of various geometrical objects heated in any medium using their centre temperature measurements in a simple and accurate manner.     

Plasma-modified multiwalled carbon nanotubes with polyaniline for glucose biosensor applications

Multiwalled carbon nanotube (MWCNT) was modified through plasma polymerization of aniline by applying different radio frequency (radio frequency (RF): 13.56?MHz) powers. The modified MWCNTs were investigated in terms of morphology, chemical structure, and thermal behaviors, indicating the formation of composites based on the surface modification of MWCNT with polyaniline (PANI). These composites were then used in amperometric glucose biosensor, which was constructed by immobilizing glucose oxidase on premodified Pt electrode with PANI/MWCNT composites. The biosensor based on the composite obtained under RF power of 60?W exhibited the high sensitivity of 54.91?µA mM^?1 cm^?2 to glucose.