Rotor resonances of high-speed permanent-magnet brushless machines

For high-speed machines, in particular, it is very important to accurately predict natural frequencies of the rotor at the design stage so as to minimize the likelihood of failure. Finite-element analysis and experimental measurements are used to establish the natural frequencies and modes of the rotor of a high-speed permanent-magnet brushless motor, and to assess the influence of leading design parameters, such as the active length, the shaft diameter and extension, the bearings, and the material properties

Effect of optimal torque control on rotor loss of fault-tolerant permanent-magnet brushless machines

A faulted phase in a fault-tolerant permanent-magnet brushless machine can result in significant torque ripple. However, this can be minimized by using an appropriate optimal torque control strategy. Inevitably, however, this results in significant time harmonics in the phase current waveforms, which when combined with inherently large space harmonics, can result in a significant eddy-current loss in the permanent magnets on the rotor. This paper describes the optimal torque control strategy which has been adopted, and discusses its effect on the eddy-current loss in the permanent magnets of four-, five-, and six-phase fault-tolerant machines

Similarities and differences of pumping conventional and self-compacting concrete

In Practice, Self-Compacting Concrete (SCC) is Considered as a Simple Extension of Conventional Vibrated Concrete (CVC) When Pumping is Concerned. the Same Equipment, Materials, Pumping Procedures and Guidelines Used for CVC Are Applied When Pumping SCC. on the Other Hand, It Has Been Clearly Shown that the Rheological Properties and the Mix Design of SCC Are Different Than CVC. Can the Same Pumping Principles Employed for CVC Be Applied for SCC? This Paper Compares the Some Published Results of Pumping of CVC with Those for SCC. a First Striking Difference between Pumping of CVC and SCC is the Flow Behaviour in the Pipes. the Flow of CVC is a Plug, Surrounded by a Lubricating Layer, While during the Flow of SCC, Part of the Concrete Volume itself is Sheared Inside the Pipe. as a Result, the Importance of Viscosity Increases in Case of SCC. Due to the Low Yield Stress of SCC, the Behaviour in Bends is Different, But Quite Complex to Study. Due to the Lower Content of Aggregate and Better Stability of SCC, as It is Less Prone to Internal Water Migration, Blocking is Estimated to Occur at Lower Frequency in Case of SCC. © RILEM 2010

Mining for viral fragments in methylation enriched sequencing data

Most next generation sequencing experiments generate more data than is required for the experimental set up. For example, methyl-CpG binding domain (MBD) affinity purification based sequencing is often used for DNA-methylation profiling, but up to 30% of the sequenced fragments cannot be mapped uniquely to the reference genome. Here we present and evaluate a methodology for the identification of viruses in these otherwise unused paired-end MBD-seq data. Viral detection is accomplished by mapping non-reference alignable reads to a comprehensive set of viral genomes. As viruses play an important role in epigenetics and cancer development, 92 (pre)malignant and benign samples, originating from two different collections of cervical samples and related cell lines, were used in this study. These samples include primary carcinomas (n=22), low- & high-grade cervical intrapeithelial neoplasia (CIN1 & CIN2/3 - n=2/n=30) and normal tissue (n=20), as well as control samples (n=17). Viruses that were detected include phages, adenoviruses, herpesviridae and HPV. HPV, which causes virtually all cervical cancers, was identified in 95% of the carcinomas, 100% of the CIN2/3 samples, both CIN1 samples and in 55% of the normal samples. Comparing the amount of mapped fragments on HPV for each HPV-infected sample yielded a significant difference between normal samples and carcinomas or CIN2/3 samples (adjusted p-values resp. < 10^-5, < 10^-5), reflecting different viral loads and/or methylation degrees in non-normal samples. Fragments originating from different HPV types could be distinguished and were independently validated by PCR-based assays with a specificity of 98% and a sensitivitity of 66%. In conclusion, although limited by the a priori knowledge of viral reference genome sequences, the proposed methodology can provide a first but substantial insight into the presence, concentration and types of methylated viral sequences in MBD-seq data without additional costs

Appraisal of Municipal Solid Waste Management, Its Effect and Resource Potential in A Semi-Urban City: a Case Study

Managing municipal solid wastes (MSW) is progressively becoming a major challenge in many cities of developing nations because of rapid urbanization and rise in population. This can be described by ineffective collection methods, inadequate coverage of the collection, processing system and inappropriate disposal. This paper presents the current state of solid waste management in a semi-urban city, its associated challenges and prospects that are within. A field work that involves the characterization and types of the waste generated, and frequency of collection was carried out within the study area. Four locations where the major waste bins are located within the city were considered. A representative sample of 280 kg was used for the waste characterization, and the results show that about 64% of the wastes are recyclable with lots of organic waste that can be used as compost. The only dump site in the city was visited in order to obtain useful information concerning the present state of solid waste management. The study revealed that there is presently no investment made to the existing development plan to introduce a modern waste management system. The study suggests new approach that could be used by institutions and government agencies for MSW management to realize a sustainable and efficient sanitation, and possible resources generation potentials that could be harnessed from the waste stream

Srs2 promotes synthesis-dependent strand annealing by disrupting DNA polymerase δ-extending D-loops.

Synthesis-dependent strand annealing (SDSA) is the preferred mode of homologous recombination in somatic cells leading to an obligatory non-crossover outcome, thus avoiding the potential for chromosomal rearrangements and loss of heterozygosity. Genetic analysis identified the Srs2 helicase as a prime candidate to promote SDSA. Here, we demonstrate that Srs2 disrupts D-loops in an ATP-dependent fashion and with a distinct polarity. Specifically, we partly reconstitute the SDSA pathway using Rad51, Rad54, RPA, RFC, DNA Polymerase δ with different forms of PCNA. Consistent with genetic data showing the requirement for SUMO and PCNA binding for the SDSA role of Srs2, Srs2 displays a slight but significant preference to disrupt extending D-loops over unextended D-loops when SUMOylated PCNA is present, compared to unmodified PCNA or monoubiquitinated PCNA. Our data establish a biochemical mechanism for the role of Srs2 in crossover suppression by promoting SDSA through disruption of extended D-loops

Level statistics of XXZ spin chains with a random magnetic field

The level-spacing distribution of a spin 1/2 XXZ chain is numerically studied under random magnetic field. We show explicitly how the level statistics depends on the lattice size L, the anisotropy parameter $\Delta$, and the mean amplitude of the random magnetic field h. In the energy spectrum, quantum integrability competes with nonintegrability derived from the randomness, where the XXZ interaction is modified by the parameter $\Delta$. When $\Delta \ne 0$, the level-spacing distribution mostly shows Wigner-like behavior, while when $\Delta$=0, Poisson-like behavior appears although the system is nonintegrable due to randomness. Poisson-like behavior also appears for $\Delta \ne 0$ in the large h limit. Furthermore, the level-spacing distribution depends on the lattice size L, particularly when the random field is weak.Comment: 4 pages, 3 figures, to be published in Phys. Rev.

Unexpected non-Wigner behavior in level-spacing distributions of next-nearest-neighbor coupled XXZ spin chains

The level-spacing distributions of XXZ spin chains with next-nearest-neighbor couplings are studied under periodic boundary conditions. We confirm that integrable XXZ spin chains mostly have the Poisson distribution as expected. On the contrary, the level-spacing distributions of next-nearest-neighbor coupled XXZ chains are given by non-Wigner distributions. It is against the expectations, since the models are nonintegrable.Comment: 4 pages, 4 figures, to be published in Physical Review