Analysis of Gear Milling at Various Speeds, Time and Feed Rates

Spur gears are the most commonly used gears for mechanical power transmission. Form-milling the tooth of involute spur gear involves specification of the cutting speed for the work piece material and feedrate of the milling cutter. The speed and feedrate selection for such cutting has a strong link with the completion period of the machining exercise, which indirectly also determines the cost of producing the gears. This paper presents a study carried out in establishing a multiple linear regression model for determining time required for form-milling an involute spur gear tooth at varying speeds and feedrates on a milling machine. Five spur gears, of 15-teeth each, with pressure angle 200, and module 2.8mm, were experimentally milled on a universal milling machine, while the time for the completion of each tooth at different speeds and feedrates were recorded and analyzed on the platform of SPSS 12.0, where the data were subjected to t-test, ANOVA analysis and optimality test. The model generated  t = f(s,f), gave coefficients β0, β1 and β2 as 0.281,  -0.005, and -0.03 respectively. The test confirmed the coefficient as being significant to the adopted model and the ANOVA analysis showed the correlation between speeds and feedrates for cutting a tooth of a spur gear.  Thus, as the cutting speed and feedrate increases,  cutting time reduces.  The model will serve as a useful tool in preparation of cost estimate in machining of involute spur gear.http://dx.doi.org/10.4314/njt.v34i1.1

An efficient handoff management scheme for mobile wireless ATM networks

A new handoff management scheme for wireless ATM networks is proposed. In this scheme, all cells are connected to their neighboring cells by permanent virtual circuits (PVCs) and to the access switch (AS) by switched virtual circuits (SVCs) which are only for new calls. Some carefully chosen cells, called rerouting cells, are also connected to the AS by PVCs. In summary, if a mobile roams to an ordinary neighboring cell, its traffic path is simply elongated by a PVC connecting the old and new cells. If a mobile roams to a rerouting cell, its traffic path is rerouted to a PVC between the AS and rerouting cell. By using PVC's for handoff calls, we can guarantee fast and seamless handoff. At the same time, our scheme improves the path efficiency by limiting the maximum number of hops that a path can be extended. Also, allowing path rerouting at a suitable time means the network resources are more efficiently utilized.published_or_final_versio

Factors influencing contraceptives use among grandmultipara in Ile-Ife, Nigeria

Objective: To determine modifiable factors that influence contraceptive usage among grandmutiparas in a South-Western Nigerian setting.Methodology: A prospective survey was done among antenatal attendees in OAUTHC from January toDecember 2006. Using interviewer administered semi-structured questionnaire data were collected from all  grandmultiparous attendees on sociodemographic characteristics, contraceptive awareness and usage, contraceptive intentions and the role of men on contraceptives usage. Data were analysed with SPSS 11.0 and result presented in descriptive statistics.Results: The prevalence of grandmultiparity was 9.04% in the studied population, and their mean age was 36.73 + 4.7years: Eighty-one percent attended secondary school, and 65% were monogamous. Despite high level of awareness (51.6-100%) contraceptive usage was low (5.9 to 40.8%). About 90% agreed that family planning improve quality of family life. While 80% had no intention for further childbearing only 36% intended to use BTL. Sex preference was the only motivation for further childbearing in all (100%) of them.Conclusion: High literacy rate in this group did not impart positively in reducing the unmet need. Increased awareness on permanent  contraception and the role of men need to be promoted. Health education that will break the negative strongholds of cultural factors has to be introduced gradually at the primary school levels.Keywords: Contraceptive usage, Grandmultiparity, Cultural factors

Oxygen-Vacancy-Induced Orbital Reconstruction of Ti Ions at the Interface of LaAlO3/SrTiO3 Heterostructures: A Resonant Soft-X-Ray Scattering Study

Resonant soft-x-ray scattering measurements have been performed to investigate interface electronic structures of (LaAlO3/SrTiO3) superlattices. Resonant scattering intensities at superlattice reflections show clear evidence of degeneracy lifting in t(2g) states of interface Ti ions. Polarization dependence of intensities indicates the energy of d(xy) states is lower by similar to 1 eV than two other t(2g) states. The energy splitting is insensitive to epitaxial strain. The orbital reconstruction is induced by oxygen vacancies and confined to the interface within two unit cells, indicating charge compensation at the polar interfaces. DOI: 10.1103/PhysRevLett.110.017401X112723Nsciescopu

Review: optical fiber sensors for civil engineering applications

Optical fiber sensor (OFS) technologies have developed rapidly over the last few decades, and various types of OFS have found practical applications in the field of civil engineering. In this paper, which is resulting from the work of the RILEM technical committee “Optical fiber sensors for civil engineering applications”, different kinds of sensing techniques, including change of light intensity, interferometry, fiber Bragg grating, adsorption measurement and distributed sensing, are briefly reviewed to introduce the basic sensing principles. Then, the applications of OFS in highway structures, building structures, geotechnical structures, pipelines as well as cables monitoring are described, with focus on sensor design, installation technique and sensor performance. It is believed that the State-of-the-Art review is helpful to engineers considering the use of OFS in their projects, and can facilitate the wider application of OFS technologies in construction industry

Korn's second inequality and geometric rigidity with mixed growth conditions

Geometric rigidity states that a gradient field which is $L^p$-close to the set of proper rotations is necessarily $L^p$-close to a fixed rotation, and is one key estimate in nonlinear elasticity. In several applications, as for example in the theory of plasticity, energy densities with mixed growth appear. We show here that geometric rigidity holds also in $L^p+L^q$ and in $L^{p,q}$ interpolation spaces. As a first step we prove the corresponding linear inequality, which generalizes Korn's inequality to these spaces

Magnetic Origin of Giant Magnetoelectricity in Doped Y-type Hexaferrite Ba0.5Sr1.5Zn2(Fe1-xAlx)(12)O-22

We investigated site-specific magnetic behaviors of multiferroic Ba0.5Sr1.5Zn2(Fe1-xAlx)(12)O-22 using Fe L-2,L-3-edge x-ray magnetic circular dichroism. The Al dopants mostly replace the Fe3+ ions at octahedral (O-h) sites, which contribute unquenched angular momenta through off-centering displacements. This replacement greatly reduces the magnetic anisotropy energy to change the magnetic order from a helical to a heliconical type with enhanced magnetoelectric susceptibility (alpha(ME)). The tetrahedral (T-d) Fe sites exhibit magnetic hysteresis distinguishable from that of the O-h sites, especially at low magnetic fields. These results provide essential clues for the heliconical order with a giant aME and multibit memory effects in the Al-doped Y-type hexaferrite.open1178sciescopu

Comparison of quantitative real time PCR with Sequencing and ribosomal RNA-FISH for the identification of fungi in Formalin fixed, paraffin-embedded tissue specimens

Background: Identification of the causative agents of invasive fungal infections (IFI) is critical for guiding antifungal therapy. Cultures remain negative in a substantial number of IFI cases. Accordingly, species identification from formalin fixed, paraffin embedded (FFPE) tissue specimens by molecular methods such as fluorescence in situ hybridisation (FISH) and PCR provides an appealing approach to improve management of patients. Methods: We designed FISH probes targeting the 28S rRNA of Aspergillus and Candida and evaluated them with type strains. Fluorescence microscopy (FM), using FISH probes and quantitative broadrange fungal PCR targeting the rRNA gene were applied to FFPE tissue specimens from patients with proven IFI in order to explore benefits and limitations of each approach. Results: PCR followed by sequencing identified a broad spectrum of pathogenic fungi in 28 of 40 evaluable samples (70%). Hybridisation of FISH probes to fungal rRNA was documented in 19 of 40 tissue samples (47.5%), including 3 PCR negative samples with low fungal burden. The use of FISH was highly sensitive in invasive yeast infections, but less sensitive for moulds. In samples with hyphal elements, the evaluation of hybridisation was impaired due to autofluorescence of hyphae and necrotic tissue background. Conclusions: While PCR appears to be more sensitive in identifying the causative agents of IFI, some PCR negative and FISH positive samples suggest that FISH has some potential in the rapid identification of fungi from FFPE tissue samples

Whole-exome sequencing reveals critical genes underlying metastasis in oesophageal squamous cell carcinoma

Oesophageal squamous cell carcinoma (ESCC) is one of the most lethal cancers, owing to a high frequency of metastasis. However, little is known about the genomic landscape of metastatic ESCC. To identify the genetic alterations that underlie ESCC metastasis, whole-exome sequencing was performed for 41 primary tumours and 15 lymph nodes (LNs) with metastatic ESCCs. Eleven cases included matched primary tumours, synchronous LN metastases, and non-neoplastic mucosa. Approximately 50–76% of the mutations identified in primary tumours appeared in the synchronous LN metastases. Metastatic ESCCs harbour frequent mutations of TP53, KMT2D, ZNF750, and IRF5. Importantly, ZNF750 was recurrently mutated in metastatic ESCC. Combined analysis from current and previous genomic ESCC studies indicated more frequent ZNF750 mutation in diagnosed cases with LN metastasis than in those without metastasis (14% versus 3.4%, n = 629, P = 1.78 × 10–5). The Cancer Genome Atlas data further showed that ZNF750 genetic alterations were associated with early disease relapse. Previous ESCC studies have demonstrated that ZNF750 knockdown strongly promotes proliferation, migration, and invasion. Collectively, these results suggest a role for ZNF750 as a metastasis suppressor. TP53 is highly mutated in ESCC, and missense mutations are associated with poor overall survival, independently of pathological stage, suggesting that these missense mutations have important functional impacts on tumour progression, and are thus likely to be gain-of-function (GOF) mutations. Additionally, mutations of epigenetic regulators, including KMT2D, TET2, and KAT2A, and chromosomal 6p22 and 11q23 deletions of histone variants, which are important for nucleosome assembly, were detected in 80% of LN metastases. Our study highlights the important role of critical genetic events including ZNF750 mutations, TP53 putative GOF mutations and nucleosome disorganization caused by genetic lesions seen with ESCC metastasis.No Full Tex