Technologies for Ultradynamic Voltage Scaling

Energy efficiency of electronic circuits is a critical concern in a wide range of applications from mobile multimedia to biomedical monitoring. An added challenge is that many of these applications have dynamic workloads. To reduce the energy consumption under these variable computation requirements, the underlying circuits must function efficiently over a wide range of supply voltages. This paper presents voltage-scalable circuits such as logic cells, SRAMs, ADCs, and dc–dc converters. Using these circuits as building blocks, two different applications are highlighted. First, we describe an H.264/AVC video decoder that efficiently scales between QCIF and 1080p resolutions, using a supply voltage varying from 0.5 V to 0.85 V. Second, we describe a 0.3 V 16-bit microcontroller with on-chip SRAM, where the supply voltage is generated efficiently by an integrated dc–dc converter.      

Genotoxicity testing of extracts from aflatoxin-contaminated peanut meal, following chemical decontamination

One of the most important concerns in the decontamination of aflatoxin-containing feed commodities is the safety of the products for food-producing animals and for human consumption of products derived from these animals. A new method, based on the use of florisil and C18 solid phase extraction columns, was developed for the preparation of extracts from decontaminated peanut meal, which allowed testing with in vitro genotoxicity assays without interference of the residual aflatoxin B₁. Recovery of degradation products in the extracts was evaluated by the use of radiolabelled \[¹⁴C]-aflatoxin B₁ (AFB₁) added to naturallycontaminated peanut meal (3.5mg AFB₁/kg). The meal was treated by a small-scale version of an industrial decontamination process based on ammoniation. Following decontamination, more than 90% of the label could not be extracted from the meal. AFB₁ accounted for about 10% of the radiolabel present in the extractable fraction, indicating a total AFB reduction of more than 99%. Decontamination of the meal by a number of other small- and industrial-scale ammonia-based processes resulted in similar efficiencies. Application of the extraction procedure resulted in AFB₁-rich and AFB₁-poor fractions, the latter containing half of the extractable decontamination products but less than 1% of the residual AFB₁. Testing in the Salmonella /microsome mutagenicity assay (TA 100, with S9-mix) of the original crude extracts and AFB1 rich fractions prepared from non-treated and decontaminated meal, showed the positive results expected from the AFB₁ contents as determined by HPLC analysis. Analysis and testing of the AFB₁-poor fractions showed that the various decontamination processes not only resulted in a successful degradation of AFB₁ but also did not produce other potent mutagenic compounds. Slight positive results obtained with these extracts were similar for the untreated and treated meals and may be due to unknown compounds originally present in the meal. Results obtained with an unscheduled DNA synthesis (UDS) and Comet assay with rat hepatocytes supported this conclusion. Positive results obtained with the micronucleus assay, using immortalized mouse hepatocytes (GKB), did not clearly reflect the mycotoxin levels and require further examination. It is concluded that the newly developed extraction procedure yields highly reproducible fractions and hence is very suitable for examining the possible formation of less potent degradation products of aflatoxins in short-term genotoxicity tests.     

Burner rig trials with nickel- and cobalt-base alloys

Selected Ni- and Co-base alloys were hot corroded in a burner rig facility at temperatures cycled from ambient to 870 or 980°C respectively for times in excess of 3000h. A diesel fuel maintained at lw/oS and doped with sea salt to 476 ppm produced characteristic hot corrosion attack at 870°C and more classical oxidation attack at 980°C. This preliminary investigation shows that the products formed on the Ni-base alloys at 980°C were cracked and dominated by local surface protrusions (“warts”). Co-base alloys did not show these features nor were they observed following tests at the lower temperature. A small % of Y in a simple Nimonic alloy reduced the extent of scale damage but did not eliminate hot-corrosion/oxidation attack.     

Impact of bounded delay on throughput in multi-hop networks

This paper presents a closed form solution relating to the impact of bounded delays on throughput in multi-hop networks. In contrast to contemporary literature that largely focuses on average delay to estimate the Quality of Service, our model focuses on an upper bound of delay, referred to as delay threshold in this paper. Traffic that exceeds the delay threshold is treated as lost throughput. The results obtained can be used in scaling resources in a multi-hop network for attaining specified levels of throughput under different thresholds of acceptable delays. Both single-hop and multi-hop transfers are addressed. The theoretical analysis presented in this paper is further corroborated by simulation. The findings presented in this paper will be very relevant to multi-hop network applications where received data that are older than a specified threshold period are not relevant and must be discarded.     

Thermal and Optical Properties of Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Te Diluted Magnetic Semiconductor Studied by Photoacoustic Spectroscopic Method

Using photoacoustic spectroscopy, the composition-dependent absorption coefficient (α), thermal diffusivity (σ), and optical bandgap (E _g) of Zn_1−x Mn _x Te diluted magnetic semiconductor have been measured. For higher Mn compositions, the absorption spectrum of the Zn–Mn–Te system consists of three regions, viz., the high absorption region, the exponential region, and the weak absorption tail. The bandgap follows a nonlinear variation with composition, showing a downward bowing with a minimum around x = 0.31 as a consequence of the electro-negativity difference between the substituted atoms. The composition-dependent band-edge effective mass of the carriers does not show the bowing behavior indicating that the momentum matrix is not the same for all the Zn_1−x Mn _x Te alloys due to different lattice constants. The absorption spectra show that the transition is allowed and direct.     

Elektromagnetisches Geräusch von Reluktanzmaschinen mit segmentiertem Läufer

Übersicht Zur Ermittlung der wichtigsten Radialkraftwellen wird anhand der in Teil 1 ausgeführten Feldberechnung eine Übersicht über die Polpaarzahlen und Frequenzen der Oberfelder erstellt. Das sich hieraus ergebende Tonfrequenzspektrum wird mit experimentellen Untersuchungen an einem 22kW-Reluktanzmotor verglichen. Die ungleichmäßige Nutteilung des Dämpferkäfigs ergibt ein dichtes Frequenzspektrum, das in Verbindung mit mechanischen Eigenfrequenzen zu hohen Geräuschpegeln führt.

---

Electromagnetic noise of reluctance machines with segmental-rotor. Part 2: Radial electromagnetic force waves and noise

Contents A survey is made on the basis of the field calculation performed in part 1 of the numbers of pole-pairs and frequencies of the harmonic magnetic fields in order to find out the most important radial force waves. The resulting audio frequency spectrum is compared to experimental investigations of a 22 kW-reluctance motor. The unequal slot pitch of the squirrel-cage damper results in a dense frequency spectrum which, in connection with the mechanical natural frequencies, causes high noise levels.

---

---

Teil 1 erschien Arch. Elektrotech. 73 (1990) 253–260     

A Novel Low-Temperature Synthesis of Nanosized NiZn Ferrite

Nanosized NiZn ferrite powder is synthesized by a low-temperature method, using a unique combination of citric acid and glycine. An appropriate molar ratio of both citric acid and glycine offers a low-temperature synthetic route by incorporating the complexation behavior of citric acid and the combustion nature of glycine. Thermal decomposition/controlled autocatalytic combustion of the composite gel occurs at a low temperature of around 175°C, with the evolution of a large amount of gases. Transmission electron microscopic studies showed that the average particle size of the ferrite obtained is ∼2.5 nm, with a narrow size distribution. Uniformly distributed fine-grained microstructure with low porosity is obtained for a sample sintered at 1000°C.