Scanning electron microscopy study of worn Al-Si alloy surfaces

A pin-on-disc machine was used to wear Al-Si alloy pins under dry conditions. Unmodified and modified binary alloys and commercial multi-component alloys were tested. The surfaces of the worn alloys were examined by scanning electron microscopy to identify distinct topographical features to aid elucidation of the mechanisms of wear.

Representation of functional dependencies in relational databases using linear graphs

Functional dependencies in relational databases are investigated. Eight binary relations, viz., (1) dependency relation, (2) equipotence relation, (3) dissidence relation, (4) completion relation, and dual relations of each of them are described. Any one of these eight relations can be used to represent the functional dependencies in a database. Results from linear graph theory are found helpful in obtaining these representations. The dependency relation directly gives the functional dependencies. The equipotence relation specifies the dependencies in terms of attribute sets which functionally determine each other. The dissidence relation specifies the dependencies in terms of saturated sets in a very indirect way. Completion relation represents the functional dependencies as a function, the range of which turns out to be a lattice. Depletion relation which is the dual of the completion relation can also represent functional dependencies and similarly can the duals of dependency, equipotence, and dissidence relations. The class of depleted sets, which is the dual of saturated sets, is defined and used in the study of depletion relations.

A non-linear analogue-to-digital converter for linearization of transducer input-output relationships

Analogue and digital techniques for linearization of non-linear input-output relationship of transducers are briefly reviewed. The condition required for linearizing a non-linear function y = f(x) using a non-linear analogue-to-digital converter, is explained. A simple technique to construct a non-linear digital-to-analogue converter, based on ' segments of equal digital interval ' is described. The technique was used to build an N-DAC which can be employed in a successive approximation or counter-ramp type ADC to linearize the non-linear transfer function of a thermistor-resistor combination. The possibility of achieving an order of magnitude higher accuracy in the measurement of temperature is shown.

Systematic Construction of Linear Transform Based Full-Diversity, Rate-One Space-Time Frequency Codes

In this paper, we generalize the existing rate-one space frequency (SF) and space-time frequency (STF) code constructions. The objective of this exercise is to provide a systematic design of full-diversity STF codes with high coding gain. Under this generalization, STF codes are formulated as linear transformations of data. Conditions on these linear transforms are then derived so that the resulting STF codes achieve full diversity and high coding gain with a moderate decoding complexity. Many of these conditions involve channel parameters like delay profile (DP) and temporal correlation. When these quantities are not available at the transmitter, design of codes that exploit full diversity on channels with arbitrary DIP and temporal correlation is considered. Complete characterization of a class of such robust codes is provided and their bit error rate (BER) performance is evaluated. On the other hand, when channel DIP and temporal correlation are available at the transmitter, linear transforms are optimized to maximize the coding gain of full-diversity STF codes. BER performance of such optimized codes is shown to be better than those of existing codes.

Linear time geometrical design rule checker based on quadtree representation of VLSI mask layouts

An efficient geometrical design rule checker is proposed, based on operations on quadtrees, which represent VLSI mask layouts. The time complexity of the design rule checker is O(N), where N is the number of polygons in the mask. A pseudoPascal description is provided of all the important algorithms for geometrical design rule verification.

New initiators for the ring-opening thermal polymerization of hexachlorocyclotriphosphazene: synthesis of linear poly(dichlorophosphazene) in high yields

Ring-opening thermal polymerization of hexachlorocyclotriphosphazene (N3P3C&h)a s been investigated at 250 "C and at 1.333-Pa pressure using chlorocyclotriphosphazenes N3P3C15(N=PPh3) and N3P3Cl,.,(NMe2), (n = 2-4), salt hydrates, triphenylphosphine, and benzoic acid as initiators. The linear poly (dich1orophosphazene) products are phenoxylated, and the phenoxy polymers are characterized by gel permeation chromatography and dilute solution viscometry. Among the various initiators investigated, CaS04.2H20b rings about a high conversion (>60%) of N3P3C&to the linear [NPC12], polymer which possesses a high molecular weight (>5 X lo6). The rationale for the choice of the initiators and possible mechanism(s) of polymerization is discussed. Several mixed substituent polymers, [NP(OPh),(OC6H4Me-p)2,1, and [NP(OPh),(OCHzCF3)2,]nh, ave been prepared and their thermal properties evaluated.

Rice molecular breeding laboratories in the genomics era: Current status and future considerations

Using DNA markers in plant breeding with marker-assisted selection (MAS) could greatly improve the precision and efficiency of selection, leading to the accelerated development of new crop varieties. The numerous examples of MAS in rice have prompted many breeding institutes to establish molecular breeding labs. The last decade has produced an enormous amount of genomics research in rice, including the identification of thousands of QTLs for agronomically important traits, the generation of large amounts of gene expression data, and cloning and characterization of new genes, including the detection of single nucleotide polymorphisms. The pinnacle of genomics research has been the completion and annotation of genome sequences for indica and japonica rice. This information-coupled with the development of new genotyping methodologies and platforms, and the development of bioinformatics databases and software tools-provides even more exciting opportunities for rice molecular breeding in the 21st century. However, the great challenge for molecular breeders is to apply genomics data in actual breeding programs. Here, we review the current status of MAS in rice, current genomics projects and promising new genotyping methodologies, and evaluate the probable impact of genomics research. We also identify critical research areas to "bridge the application gap" between QTL identification and applied breeding that need to be addressed to realize the full potential of MAS, and propose ideas and guidelines for establishing rice molecular breeding labs in the postgenome sequence era to integrate molecular breeding within the context of overall rice breeding and research programs.

A New PWM Control Method for Three-Phase Autosequentially Commutated Current Source Inverters

A new current pulsewidth modulation (PWM) method is presented which uses the principle of creating zero three-phase currents at selected instants of time, through which the load current harmonic content can be controlled along with the magnitude of its fundamental content. This gives rise to reduction of motor torque ripples through the selection of suitable PWM patterns and a fast current control in the inverter by varying the pulsewidths of the PWM pattern. Under this new PWM mode of operation, the autosequentially commutated inverter (ASCI) circuit can be modified easily so that a higher number of pulses can be accomodated within a half-cycle, compared to the normal ASCI circuit. The experimental oscillograms verify the effectiveness of the new PWM method.

Non-linear resonance in strings under narrow band random excitation, part I: Planar response and stability

Non-linear planar response of a string to planar narrow band random excitation is investigated in this paper. A response equation for the mean square deflection σ2 is obtained under a single mode approximation by using the equivalent linearization technique. It is shown that the response is triple valued, as in the case of harmonic excitation, if the centre frequency of excitation Ω lies in a certain specified range. The triple valued response occurs only if the excitation bandwidth β is smaller than a critical value βcrit which is a monotonically increasing function of the intensity of excitation. An approximate method of investigating the almost sure asymptotic stability of the solution is presented and regions of instability in the Ω-σ2 plane have been charted. It is shown that planar response can become unstable either due to an unbounded growth of the in-plane component of motion or due to a spontaneous appearance of an out-of-plane component.

The ACA effect: Examining how current affairs programs shape victim understandings and responses to online fraud

In recent years, numerous current affairs stories on online fraud victimisation have been broadcast on Australian television. These stories typically feature highly organised, international ‘sting’ operations, in which alleged offenders are arrested and investigated by law enforcement. These portrayals of police responses influence the expectations that some online fraud victims have about how their individual cases will be handled by law enforcement. Based on interviews with 80 online fraud victims, this article argues that a narrow media portrayal of online fraud by television current affairs programs — termed the ‘ACA effect’ — informs victims’ understandings of online fraud and their responses to it. In particular, current affairs programs influence what victims of online fraud expect from police. The article further demonstrates that current affairs programs present themselves as de facto law enforcement agencies, to which victims who receive an unsatisfactory response from police might turn. Overall, the article highlights the importance of current affairs programs portraying a more realistic image of official responses to online fraud.

Measurement and Interpretation of Salinity Tolerance in Four Perennial Grasses

Whilst the topic of soil salinity has received a substantive research effort over the years, the accurate measurement and interpretation of salinity tolerance data remain problematic. The tolerance of four perennial grass species (non-halophytes) to sodium chloride (NaCl) dominated salinity was determined in a free-flowing sand culture system. Although the salinity tolerance of non-halophytes is often represented by the threshold salinity model (bent-stick model), none of the species in the current study displayed any observable salinity threshold. Further, the observed yield decrease was not linear as suggested by the model. On re-examination of earlier datasets, we conclude that the threshold salinity model does not adequately describe the physiological processes limiting growth of non-halophytes in saline soils. Therefore, the use of the threshold salinity model is not recommended for non-halophytes, but rather, a model which more accurately reflects the physiological response observed in these saline soils, such as an exponential regression curve.

Development of a vaccine for Chlamydia trachomatis: Challenges and current progress

Chlamydia trachomatis remains an enigmatic bacterial pathogen with no vaccine yet available to treat human ocular and genital tract infections caused by tissue-tropic serovars of the organism. Globally, it is the leading cause of preventable blindness as well as the leading cause of bacterial sexually transmitted infections. The pathogen has a range of virulence factors that enable it to successfully evade both the innate and adaptive immune system of the host. The host immune system, although protective, paradoxically is also associated closely with the pathologies of trachoma and pelvic inflammatory disease – disease sequelae of some chlamydial infections and reinfections in some genetically susceptible hosts. In this review, we focus on what is known currently about the pathogenesis of ocular and genital infections caused by this mucosal pathogen. We also discuss novel insights into the pathogenesis of infections caused by the genital and ocular serovars of C. trachomatis, including a discussion of both pathogen and host factors, such as the human microbiota at these mucosal sites as well as the current immunological challenges facing vaccine development. Finally, we discuss the current progress toward development of a vaccine against C. trachomatis. A wide range of recombinant protein antigens are being identified and, hence, are available for vaccine trials. A plasmid-free live strain has recently been produced and evaluated in the mouse (Chlamydia muridarum) and monkey (C. trachomatis) models. The data for ocular infections in the monkey model was particularly encouraging, although the path to regulatory approval of a live vaccine is still uncertain. While still a major challenge, vaccines for ocular and genital C. trachomatis infections are looking more promising.

A new algorithm for parallel solution of linear equations

Abstract is not available.

Reassessing the earthquake hazard in Kerala based on the historical and current seismicity

Given the lack of proper constraints in understanding earthquake mechanisms in the cratonic interiors and the general absence of good quality database, here we reassess the seismic hazard in the province of Kerala, a part of the aEuro cent stable continental interioraEuro cent, based on an improved historical and instrumental database. The temporal pattern of the current seismicity suggests that > 60% of the microtremors in Kerala occurs with a time lag after the peak rainfall, indicating that hydroseismicity may be a plausible model to explain the low-level seismicity in this region. Further, an increment in overall seismicity rate in the region in the recent years is explained as due to increased anthropogenic activities, which includes changes in hydrological pathways as a consequence of rapid landscape changes. Our analyses of the historical database eliminate a few events that are ascribed to this region; this exercise has also led to identification of a few events, not previously noted. The improved historical database essentially suggests that the central midland region is more prone to seismic activity compared to other parts of Kerala. This region appears to have generated larger number of significant earthquakes; the most prominent being the multiple events (doublets) of 1856 and 1953, whose magnitudes are comparable to that of the 2000/2001 (central Kerala) events. Occurrences of these historical events and the recent earthquakes, and the local geology indicative of pervasive faulting as shown by widely distributed pseudotachylite veins suggest that the NNW-SSE trending faults in central midland Kerala may host discrete potentially active sources that may be capable of generating light to moderate size earthquakes. The frequency of earthquakes in central Kerala evident from the historical database requires that the seismic codes stipulated for this region are made mandatory.

Nutritional management for reproductive efficiency

Nutrition influences reproductive efficiency and the survival of lambs and weaners but the costs of supplementary feeding or maintaining low stocking rates are not justified by the resulting income from higher lamb weaning rates and reduced weaner mortality. The current practice of segmenting the ewe flock using ultrasound scanning to determine the number of foetuses still results in groups of ewes with a wide range of condition scores and with widely differing nutritional requirements. This report describes an approach to precision management of pregnant ewes and weaners that is based on the e-sheep platform of technologies and uses computer-directed drafting for nutritional management of individual animals and walk-through weighing to monitor changing nutritional status. It is estimated that the cost of feeding a thousand-ewe flock can be reduced from $14,000 for feeding all animals to $3300 for targeted feeding of 25% of ewes requiring additional nutrition and 20% of weaners at risk of dying. The cost of the targeted feeding strategy is more than justified by the value of additional 12-month-old animals, which is $9000. The e-sheep precision nutrition system is not attractive to industry at this stage because of the cost of the e-sheep infrastructure, the perceived complexity of the technology and the requirement for further research, but it is expected to be a commercial option within three years.