2,322 research outputs found
Evalaution and optimization of laser cutting parameters for plywood materials
Laser process parameters influence greatly the width of kerfs and quality of the cut edges. This article reports experiments on the laser plywood-cutting performance of a CW 1.5 kW CO2¬ Rofin laser, based on design of experiments (DOE). The laser was used to cut three thicknesses 3, 6 and 9 mm of plywood panels. The process factors investigated are: laser power, cutting speed, air pressure and focal point position. The aim of this work is to relate the cutting edge quality parameters namely: upper kerf (UK), lower kerf (LK), the ratio between upper to lower kerfs and the operating cost to the process parameters mentioned above. Mathematical models were developed to establish the relationship between the process parameters and the edge quality parameters, and special graphs were drawn for this purpose. Finally, a numerical optimization was performed to find out the optimal process setting at which both kerfs would lead to a ratio of about 1, and at which low cutting cost take place
Associations of the objective built environment along the route to school with children's modes of commuting: A multilevel modelling analysis (the SLIC study).
As active commuting levels continue to decline among primary schoolchildren, evidence about which built environmental characteristics influence walking or cycling to school remains inconclusive and is strongly context-dependent. This study aimed to identify the objective built environmental drivers of, and barriers to, active commuting to school for a multi-ethnic sample of 1,889 healthy primary schoolchildren (aged 5-11) in London, UK. Using cross-sectional multilevel ordered logistic regression modelling, supported by the spatial exploration of built environmental characteristics through cartography, the objective built environment was shown to be strongly implicated in children's commuting behaviour. In line with earlier research, proximity to school emerged as the prime variable associated with the choice for active commuting. However, other elements of the urban form were also significantly associated with children's use of active or passive modes of transport. High levels of accidents, crime and air pollution along the route to school were independently correlated with a lower likelihood of children walking or cycling to school. Higher average and minimum walkability and higher average densities of convenience stores along the way were independently linked to higher odds of active commuting. The significance of the relations for crime, air pollution and walkability disappeared in the fully-adjusted model including all built environmental variables. In contrast, relationships with proximity, traffic danger and the food environment were maintained in this comprehensive model. Black children, pupils with obesity, younger participants and those from high socioeconomic families were less likely to actively commute to school. There is thus a particular need to ensure that roads with high volumes of actively commuting children are kept safe and clean, and children's exposure to unhealthy food options along the way is limited. Moreover, as short commuting distances are strongly correlated with walking or cycling, providing high-quality education near residential areas might incite active transport to school
Audit Costs for the 1986 Texas Energy Cost Containment Program
Direct program costs for detailed audits of
13.5 million square feet of institutional building
space in the 1986 Texas Energy Cost Containment
Program were 0.050/SF. Large medical buildings (greater
than about 170,000 square feet) were audited for
0.0028/SF. The effect on audit costs of
complexity of recommended modifications, amount of
savings determined, amount of implementation
costs, building size, and building complexity are
discussed. Primary effects on audit costs are
size and complexity of buildings. Program
guidelines limited consideration of projects with
greater than a four year payback
Overview of Highland Valley Tailings Storage Facility
This paper presents key features of the Highland Valley tailings storage facility comprising two tailings dams, a 107 m high H-H Dam and a 166 m high L-L Dam. The construction history to date including instrumentation observations is also reviewed. Although the tailings facility is situated in a low to moderate seismic area within the Interior Plateau of British Columbia, potential earthquake sources that might have an impact on the site have been carefully assessed. Both dams are designed to have adequate seismic resistance against design earthquakes appropriate for the site. The L-L Dam valley section, involving soft lacustrine deposits beneath the Starter Dam, has been buttressed by a compacted downstream berm founded on dense glacial till. As the geometry of the tailings storage and distribution facilities and waste dumps changes with time, the quantity and relative cost of various construction materials including natural borrow, cycloned sand and pit overburden also change. Ongoing construction is planned to maintain key earthquake and flood design criteria as well as to adjust the use and placement method of various materials to achieve an efficient and cost effective tailings storage operation. Inherent in the design of the two tailings dams, both constructed by the centerline method, is the flexibility which enables the storage capacity of the tailings facility to be increased beyond the present 1.8 billion tonnes if required at some future time
Robust Upward Dispersion of the Neutron Spin Resonance in the Heavy Fermion Superconductor CeYbCoIn
The neutron spin resonance is a collective magnetic excitation that appears
in copper oxide, iron pnictide, and heavy fermion unconventional
superconductors. Although the resonance is commonly associated with a
spin-exciton due to the ()-wave symmetry of the superconducting
order parameter, it has also been proposed to be a magnon-like excitation
appearing in the superconducting state. Here we use inelastic neutron
scattering to demonstrate that the resonance in the heavy fermion
superconductor CeYbCoIn with has a ring-like
upward dispersion that is robust against Yb-doping. By comparing our
experimental data with random phase approximation calculation using the
electronic structure and the momentum dependence of the -wave
superconducting gap determined from scanning tunneling microscopy for
CeCoIn, we conclude the robust upward dispersing resonance mode in
CeYbCoIn is inconsistent with the downward dispersion
predicted within the spin-exciton scenario.Comment: Supplementary Information available upon reques
Molecular evidence of synaptic pathology in the CA1 region in schizophrenia.
Alterations of postsynaptic density (PSD)95-complex proteins in schizophrenia ostensibly induce deficits in synaptic plasticity, the molecular process underlying cognitive functions. Although some PSD95-complex proteins have been previously examined in the hippocampus in schizophrenia, the status of other equally important molecules is unclear. This is especially true in the cornu ammonis (CA)1 hippocampal subfield, a region that is critically involved in the pathophysiology of the illness. We thus performed a quantitative immunoblot experiment to examine PSD95 and several of its associated proteins in the CA1 region, using post mortem brain samples derived from schizophrenia subjects with age-, sex-, and post mortem interval-matched controls (n=20/group). Our results indicate a substantial reduction in PSD95 protein expression (-61.8%). Further analysis showed additional alterations to the scaffold protein Homer1 (Homer1a: +42.9%, Homer1b/c: -24.6%), with a twofold reduction in the ratio of Homer1b/c:Homer1a isoforms (P=0.011). Metabotropic glutamate receptor 1 (mGluR1) protein levels were significantly reduced (-32.7%), and Preso, a protein that supports interactions between Homer1 or PSD95 with mGluR1, was elevated (+83.3%). Significant reduction in synaptophysin (-27.8%) was also detected, which is a validated marker of synaptic density. These findings support the presence of extensive molecular abnormalities to PSD95 and several of its associated proteins in the CA1 region in schizophrenia, offering a small but significant step toward understanding how proteins in the PSD are altered in the schizophrenia brain, and their relevance to overall hippocampal and cognitive dysfunction in the illness
Density fluctuations and the structure of a nonuniform hard sphere fluid
We derive an exact equation for density changes induced by a general external
field that corrects the hydrostatic approximation where the local value of the
field is adsorbed into a modified chemical potential. Using linear response
theory to relate density changes self-consistently in different regions of
space, we arrive at an integral equation for a hard sphere fluid that is exact
in the limit of a slowly varying field or at low density and reduces to the
accurate Percus-Yevick equation for a hard core field. This and related
equations give accurate results for a wide variety of fields
- …