Long Distance Wireless Networking for Site - Office Data Communications

Effective data communications between the project site and decision making office can be critical for the success of a construction project. It allows convenient access to centrally stored information and allows centrally located decision makers to remotely monitor the site and collect data in real-time. However, high bandwidth, flexible data communication networks, such as wired local area networks, can often be time-consuming and costly to deploy for such purposes especially when project sites (dams, highways, etc.) are located in rural, undeveloped areas where networking infrastructure is not available. In such construction sites, wireless networking could reliably link the construction site and the decision-making office. This paper presents a case study on long-distance, site – office wireless data communications. The purpose was to investigate the capability of wireless technology in exchanging construction data in a fast and efficient manner and in allowing site personnel to interact and share knowledge and data with the office staff. This study took place at the University of Michigan’s campus where performance, reliability, and cost/benefit tests were performed. The indoor and outdoor tests performed demonstrated the suitability of this technology for office-site data communications and exposed the need for more research to further improve the reliability and data handling of this technology.

Hydroacoustic study of spatial and temporal distribution of Gymnocypris przewalskii (Kessler, 1876) in Qinghai Lake, China

Gymnocypris przewalskii (Kessler 1876) is an endangered and state-protected rare fish species in Qinghai Lake, China. To further understand the life history and distribution of this fish, five surveys were carried out in Qinghai Lake between 2002-2006. Results of these surveys indicate that fishes were predominantly distributed about 2 m under the surface. In July, significant differences in fish density were found between surface and bottom layers (P = 0.001), and/or between middle and bottom layers (P = 0.025). Fish density was the greatest in the surface layer. In August and October, no significant differences were found between the different layers, but the bottom layer had a greater fish density. Furthermore, there were very large differences among different zones in fish distribution density. Differences in horizontal distribution were not significantly correlated to factors such as water depth and inshore distance, possibly because of very low and uniform fish density. Feeding, changes in water temperature, over-wintering and spawning appeared to influence fish distribution. Hydroacoustic estimates of G. przewalskii biomass in Qinghai Lake increased significantly between 2002 and 2006. We attribute this increase to the management measures put in place to protect this species.

Estimated detection distance of a baiji's (Chinese river dolphin, Lipotes vexillifer) whistles using a passive acoustic survey method

Source levels and phonation intervals of whistles produced by a free-ranging baiji (Chinese river dolphin) were measured in the seminatural reserve of Shishou in Hubei, China. A total of 43 whistles were recorded over 12 recording sessions. The mean dominant frequency (the frequency at the highest energy) was 5.7 kHz (s.d.=0.67). The calculated source level was 143.2 dB rms re 1 mu Pa (s.d.=5.8). Most phonation intervals were shorter than 460 s, and the average interval was 205 s (s.d. = 254). Theoretical detection range of baiji's whistle was 6600 m at the present study site, but it could reduce a couple of hundred meters in practical noisy situation in the Yangtze River. Sporadic phonation (205 s interval on average) with relatively faint signal of baiji was considered, to be difficult to be detected by a towing hydrophone system. Stationed monitoring or slow speed towing of hydrophones along the river current is recommended. (c) 2006 Acoustical Society of America.

A study on the realization of radio frequency energy AC/DC charge pump based on MOS FET

This paper presents a novel efficient charge pump composed of low Vth metal-oxide-semiconductor (MOS) field effect transistors (FET) in the course of realizing radio frequency (RF) energy AC/DC conversion. The novel structure eliminates those defects caused by typical Schottky-diode charge pumps, which are dependent on specific processes and inconsistent in quality between different product batches. Our analyses indicate that an easy-fabricated, stable and efficient RF energy AC/DC charge pump can be conveniently implemented through reasonably configuring the MOS transistor aspect ratio, and other design parameters such as capacitance, multiplying stages to meet various demands on performance.

Effects of phase-breaking on long-range charge transfer in DNA: Partially-coherent-tunneling model study

The mechanism of hole charge transfer in DNA of various lengths and sequences is investigated based on a partially coherent tunneling theory (Zhang et al., J Chem Phys 117:4578, 2002), where the effects of phase-breaking in adenine-thymine and guanine-cytosine base pairs are treated on equal foot. This work aims at providing a self-consistent microscopic interpretation for rate experiments on various DNA systems. We will also clarify the condition under which the simple superexchange-mediated-hopping picture is valid, and make some comments on the further development of present theory.

Theoretical Study on the Butt-coupling of Semiconductor Laser and Fiber Bragg Grating

The butt-coupling between a semiconductor laser diode and a fiber Bragg grating external cavity acts a key roll on the laser characteristics. The scatter matrix method considering the butt-coupling efficiency is used to analyze the butt-coupling between them. It is found that the butt-coupling distance and coupling efficiency determine the laser characteristics. For strong feedback, the single lasing wavelength changes in the reflection bandwidth of the effective reflectivity ( approximately the Bragg region of the fiber Bragg grating) as the distances change. For weak feedback condition, some different results are obtained. The SMSRs in the two conditions are presented and analyzed. These results can provide important design guidance of device parameters for the practical fabrication.

Study on Water Resources Regulation and Reservoir Operating Prediction for Suppression of Salt Water Intrusion in the Pearl River Estuary

Salt water intrusion occurred frequently during dry season in Modaomen waterway of the Pearl River Estuary. With the development of region's economy and urbanization, the salt tides affect the region's water supply more and more seriously in recent years. Regulation and allocation of freshwater resources of the upper rivers of the estuary to suppress the salt tides is becoming important measures for ensuring the water supply security of the region in dry season. The observation data analysis showed that the flow value at the Wuzhou hydrometric station on the upper Xijiang river had a good correlation with the salinity in Modaomen estuary. Thus the flow rate of Wuzhou has been used as a control variable for suppression of salt tides in Modaomen estuary. However, the runoff at Wuzhou mainly comes from the discharge of Longtan reservoir on the upper reaches of Xijiang river and the runoff in the interval open valley between Longtan and Wuzhou sections. As the long distance and many tributaries as well as the large non-controlled watershed between this two sections, the reservoir water scheduling has a need for reasonable considering of interaction between the reservoir regulating discharge and the runoff process of the interval open watershed while the deployment of suppression flow at Wuzhou requires longer lasting time and high precision for the salt tide cycles. For this purpose, this study established a runoff model for Longtan - Wuzhou interval drainage area and by model calculations and observation data analysis, helped to understand the response patterns of the flow rate at Wuzhou to the water discharge of Longtan under the interval water basin runoff participating conditions. On this basis, further discussions were taken on prediction methods of Longtan reservoir discharge scheduling scheme for saline intrusion suppression and provided scientific and typical implementation programs for effective suppression flow process at the Wuzhou section.

Drift distance survey in direct plasma injection scheme for high current beam production

In a laser ion source, plasma drift distance is one of the most important design parameters. Ion current density and beam pulse width are defined by plasma drift distance between a laser target and beam extraction position. In direct plasma injection scheme, which uses a laser ion source and a radio frequency quadrupole linac, we can apply relatively higher electric field at beam extraction due to the unique shape of a positively biased electrode. However, when we aim at very high current acceleration such as several tens of milliamperes, we observed mismatched beam extraction conditions. We tested three different ion current at ion extraction region by changing plasma drift distance to study better extraction condition. In this experiment, C6+ beam was accelerated. We confirmed that matching condition can be improved by controlling plasma drift distance.

On the propagation rate of the chemical waves observed during the course of CO oxidation on a Ag/Pt(110) composite surface

We have analyzed the propagation rate of the chemical waves observed during the course of CO oxidation on a Ag/Pt(I 10) composite surface that were reported in our previous papers [Surf Interface Anal. 2001, 32, 179; J. Phys. Chem. B 2002, 106, 5645]. In all cases, the propagation rate v can be adequately fitted as v = v(0) + D-0/d, in which v(0) and D-0 are constants, and d is the distance between the reaction front of the chemical wave and the boundary from which the chemical wave originates. We propose that the surface species responsible for the formation of the chemical wave comes from two paths: the adsorption of molecules in the gas phase on the surface and the migration from the adjacent surface with different catalytic activity. v(0) corresponds to the contribution from the surface species due to the adsorption, and D-0/d to that of the surface species that migrates from the adjacent surface. The rate equation clearly suggests that the observed chemical wave results from the coupling between adjacent surfaces with different catalytic activities during the course of heterogeneous catalysis. These results, together with our previous reports, provide a good fundamental understanding of spillover, an important phenomenon in heterogeneous catalysis.

Nanoparticle-amplified Surface Plasmon Resonance Study of Protein Conformational Change at Interface

This paper reports the study of protein conformational change by Au nanoparticles (AUNPs)-amplified surface plasmon resonance (SPR) spectroscopy. Taking cytochrome c (Cyt c) as an example, this paper gives a detailed description of the construction of metal-protein-metal sandwich nanostructure consisting of an Au film underlayer, a cytochrome c intermediate layer and an AuNPs upper layer. The incorporation of AuNPs into SPR biosensing results in increased SPR sensitivity to protein conformational change as demonstrated by acid denaturation of Cyt c. It suggests the conformational change of surface-confined Cyt c leads to the distance and electromagnetic coupling variations of Au film-AuNPs.

Structural evolution of tensile-deformed high-density polyethylene during annealing: Scanning synchrotron small-angle X-ray scattering study

The structural evolution of high-density polyethylene subjected to uniaxial tensile deformation was investigated as a function of strain and after annealing at different temperatures using a scanning synchrotron small-angle X-ray scattering (SAXS) technique. The results confirm that in the course of tensile deformation intralamellar block slips were activated at small deformations followed by a stress-induced fragmentation and recrystallization process yielding thinner lamellae with their normal parallel to the stretching direction. The original sheared lamellae underwent severe internal deformation so that they were even less stable than the newly developed thinner lamellae. Accordingly, annealing results in a melting of the original crystallites even at moderate strains where the stress-induced fragmentation and recrystallization just sets in and generates a distinctly different form of lamellar stacks aligned along the drawing direction. It was found that the lamellae newly formed during stretching at moderate strains remain stable at lower temperature. Only at a very high annealing temperature of 120 degrees C can they be melted, leading to an isotropic distribution of the lamellar structure.

Study of controllable aggregation morphology of ABA amphiphilic triblock copolymer in dilute solution by changing the solvent property

We have studied, both experimentally and theoretically, the aggregation morphology of the ABA amphiphilic triblock copolymer in dilute solution by changing the solvent property. Experimental results showed that the micellar morphology changed from spheres to rods and then to vesicles by changing the common solvent from N-N-dimethylformamide (DMF) to dioxane and then to tetrahydrofuran (THF). These controllable aggregates were also obtained by Monte Carlo simulation. The simulative results showed that the solvent property is a key factor that determines the copolymer aggregation morphology. The morphology changed from spheres to rods and then to vesicles by increasing the solvent solubility, corresponding to the change of stretched of the copolymer chains in the micellar cores. This result is in good agreement with the experimental one. Moreover, the simulative results revealed that the end-to-end distant of the ABA triblock copolymer in the vesicle was larger than that in the spheres and rods, indicating that the copolymer chains were more stretched in vesicles than in the spheres and rods. Furthermore, we gave the distribution of the fraction of the chain number with the end-to-end distance. The results indicated that the amount of folded chains is almost the same as that of stretched chains in the vesicle. Although most chains were folded, stretched chains could be found in the rod and sphere micelles.

Density functional study of the second row transition metal dimers

Equilibrium geometries, vibrational frequencies and dissociation energies of the second row transition metal dimers (from Y-2 to Cd-2 except Tc-2) ere studied by use of density functional methods B3LYP, BLYP, B3PW91, BHLYP, BP86, B3P86, SVWN, MPW1PW91 and PBE1PBE. The accuracy DFT methods is found to be highly dependent on the functional employed, in particular for vibrational frequency and dissociation energy. In most cases, the predicted bond distance is in general agreement with experiment and previous theoretical results. For van der Waals dimer Cd-2, B3LYP and BLYP have excellent performance in predicting the bond distance. For Ag-2, all density functional methods used in this study perform well in producing the bond distance, vibrational frequency and dissociation energy.

Density-functional study of lanthanum, ytterbium, and lutetium dimers

La-2, Yb-2, and Lu-2 have been studied by use of the density-functional methods B3LYP, BLYP, B3PW91, BHLYP, BP86, B3P86, MPW1PW91, and PBE1PBE. In these density-functional methods, the exchange functional is from either Becke's three-parameter HF-DFT hybrid exchange functional (B3), pure DFT exchange functional of 1988 (B), a modification of the half-and-half HF/DFT hybrid method (BH), Perdew-Wang 1991 (PW91), or Barone's modified PW91 (MPW1), while the correlation functional is from either Lee, Yang, and Parr (LYP), Perdew-Wang 1991 (PW91), or Perdew 86 (P86). PBE1PBE is the generalized-gradient-approximation exchange-correlation functional of Perdew, Burke, and Ernzerhof. For La-2, the calculated bond distance is in reasonable agreement with the experiment, but the calculated vibrational frequency is underestimated significantly compared with the experiment. Only BP86 and B3P86 have the best performance in reproducing the experimental dissociation energy for La-2. For the van der Waals dimer Yb-2, three functionals, B3LYP, BLYP, and BHLYP have excellent performance in reproducing the spectroscopic constants compared with both the experiment and previous theoretical studies.

In vitro study on the binding of neutral red to bovine serum albumin by molecular spectroscopy

In this paper, the binding of neutral red (NR) to bovine serum albumin (BSA) under physiological conditions has been studied by spectroscopy method including fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. The Stern-Volmer fluorescence quenching constant (K-SV), binding constant (K-b) and the number of binding sites (It) were measured by fluorescence quenching method. Fluorescence experiments were also performed at different ionic strengths. It was found K-SV was ionic strength dependent, which indicated the electrostatic interactions were part of the binding forces. The distance r between donor (BSA) and acceptor (NR) was obtained according to Foster's non-radiative energy transfer theory. CD spectroscopy and FT-IR spectroscopy were used to investigate the structural information of BSA molecules on the binding of NR, and the results showed no change of BSA conformation in our experimental conditions.