Contour Following for Scanning Control in SFF Application : Control Trajectory Planning

Geometric contour following for scanning control in SFF application is used to refine the boundary ofthe parts for increasing the accuracy or to develop the capability to arrange various scanning directions and paths for improving the part strength. The scanners must be driven to follow the prescribed path as fast as possible, limited by available torques. In this paper the minimum time optimal control problem with specified path and limited control torque is formulated. According to the trade-off between various requirements, a control strategy is studied.Mechanical Engineerin

Design of a High Temperature Workstation for the Selective Laser Sintering Process

Mechanical Engineerin

Penta-quark states with hidden charm and beauty

More and more hadron states are found to be difficult to be accommodated by the quenched quark models which describe baryons as 3-quark states and mesons as antiquark-quark states. Dragging out an antiquark-quark pair from the gluon field in hadrons should be an important excitation mechanism for hadron spectroscopy. Our recent progress on the penta-quark states with hidden charm and beauty is reviewed.Comment: Plenary talk at the 5th Asia-Pacific Conference on Few-Body Problems in Physics 2011 (APFB2011), 22-26 Aug., 2011, Seoul, Kore

Effect of microstructures on the electron-phonon interaction in the disordered metals Pd60_{60}Ag40_{40}

Using the weak-localization method, we have measured the electron-phonon scattering times $\tau_{ep}$ in Pd$_{60}$Ag$_{40}$ thick films prepared by DC- and RF-sputtering deposition techniques. In both series of samples, we find an anomalous $1/\tau_{ep} \propto T^2\ell$ temperature and disorder dependence, where $\ell$ is the electron elastic mean free path. This anomalous behavior cannot be explained in terms of the current concepts for the electron-phonon interaction in impure conductors. Our result also reveals that the strength of the electron-phonon coupling is much stronger in the DC than RF sputtered films, suggesting that the electron-phonon interaction not only is sensitive to the total level of disorder but also is sensitive to the microscopic quality of the disorder.Comment: accepted for publication in Phys. Rev.

Impact of repeated addition of swine manure and cattle manure on Cu and Zn amount and distribution in a Saskatchewan soil

Non-Peer ReviewedIncreasing use of animal manures in Saskatchewan requires information on the fate and distribution of residual manure copper (Cu) and zinc (Zn) in Saskatchewan soils. To address this issue, the amounts of soil Cu and Zn in various inorganic and organic fractions were investigated in a field crop research plot (Cudworth association soil) with a five year history of annual application of liquid swine manure and solid cattle manure, and in two grassland field research plots (Meota and Oxbow association soils) that had received annual application of liquid swine manure for three years. The annual rates of manure application were based on N contents in the manures, and were equivalent to approximately 0, 100, 200 and 400 kg total N ha-1 yr-1 in the field crop plots, and 0 and 100 kg total N ha-1 yr-1 in grassland plots. In both the field crop and grassland manured plots there were no substantial increases in total Cu and Zn in soils associated with manure application. Some increases in the moderately labile Cu and Zn fractions were observed in treatments with large amounts of animal manures applied every year. The liquid swine manure had less effect on increasing labile Cu and Zn fractions than cattle manure. These results indicate that annual addition of animal manures at rates of approximately 100 kg N ha-1 for 3 to 5 years does not constitute an environmental risk from Cu and Zn loading in these soils

Analysis of the influence of module construction upon forward osmosis performance

The potential of a commercial forward osmosis (FO) module to recover water from NEWater brine, an RO retentate, was assessed by taking an innovative approach to obtaining the mass transfer coefficients. The performance comparison of the spiral wound (S-W) FO module with that of the flat sheet laboratory unit suggests that the winding involved in S-W construction can adversely affect performance; the values for the S-W mass transfer coefficients were half of those expected. This first-of-its-kind performance comparison utilised coupons of the membrane and spacers taken from the module. The module was used both in the conventional manner for FO and in the reverse manner with the active layer facing the draw solution. Estimates of membrane parameters and mass transfer coefficients experiments for the two orientations were obtained using pure water, 10 mM and 25 mM NaCl solution on the feed side and 1 M NaCl as draw solution. The fouling potential of NEWater brine per se was found to be low. These are the first results with a S-W module that suggest potential for this niche application; nevertheless the level of the water flux through the S-W module clearly indicates that industrial applications of S-W FO will be constrained to special cases

Phosphorus amounts and distribution in soil as influenced by five years of repeated addition of liquid swine manure and solid cattle manure in east-central Saskatchewan

Non-Peer ReviewedLand application of livestock manure is usually considered for N needs of crops (Gburek et al. 2000). Although the N:P ratio in animal manures and effluent exhibit wide variations due to different sources and stockpiling, the manure N:P ratio is often smaller than the N:P uptake ratio of most crops (Gburek et al. 2000). It is reported that the average N:P ratio in manure from various cattle feedlots was around 2.7 (Watts et al., 1994; Eghball et al., 1997), while N:P grain uptake ratios in winter wheat, corn, and grain sorghum were 4.5, 5.9, and 4.5 respectively (Gilbertson et al., 1979). Thus, accumulation of P in soils may increase the risk of P escape from the soil system before it is used by subsequent crops (Sharpley et al., 1994; Lennox et al., 1997; Schoenau et al., 1999; Sims et al. 2000). A single application of swine manure at either low and high rates in Saskatchewan was found to have no significant impacts on increasing labile P forms in a Black Chernozemic soil (Qian and Scheonau. 2000a). However, after several years of application of animal manures, especially cattle manure, concerns over P loading have been brought to the attention of the livestock industry in Western Canada. Numerous reports show that long-term use of cattle manures and fertilizer P sources alter the amounts and distribution of P in the various pools of soil P, especially at higher P rates (Dormaar and Sommerfeldt, 1986; McKenzie et al., 1992a; Dormaar and Chang, 1995; Zheng et al, 2001). However, few studues have examined the effects of liquid swine manure addition on P distribution in prairie soils. The objective of this study was to evaluate and compare the effects of repeated applications of solid cattle manure and liquid swine manure on the amounts and distribution of P among various chemically distinguishable labile and stable P fractions in a Black Chernozemic soil in east-central Saskatchewan

Dispersal patterns of endogenous bacteria among grass carp (Ctenopharyngodon idellus) guts

The formation and regulation of vertebrate endogenous intestinal microbiota has been widely studied as the microbiota plays a crucial role in the host nutrition, development, and health. Despite the importance of microbiota for host health, it is still unclear whether the endogenous intestinal microorganisms are genetically distinct or whether they are genetically related with each other in different host individuals. In the present study, the dispersal situation of the endogenous intestinal bacteria in grass carp was investigated by constructing bacterial 16S rRNA gene clone libraries. The results indicate that the bacteria harbored in the grass carp gut could be separated into the following two groups: a- the private operational taxonomic units (OTUs), which include Cetobacterium somerae, Aeromonas jandaei, Citrobacter freundii, Achromobacter xylosoxidans and Bacteroides species; b- the shared OTUs, which include Vibrio cholerae, Plesiomonas shigelloides and Pasteurella speices. The results obtained in this investigation provide valuable information for assessing the mechanism of spread of the endogenous intestinal bacteria, especially the pathogenic ones. However, the mechanisms involved in different modes of bacterial dispersal in the grass carp gut still require further research

Triply Threaded [4]Rotaxanes

[4]Rotaxanes featuring three axles threaded through a single ring have been prepared through active metal template synthesis. Nickel-catalyzed sp3-sp3 homocouplings of alkyl bromide ‘half threads’ through 37- and 38-membered 2,2':6',2"-terpyridyl macrocycles generates triply-threaded [4]rotaxanes in up to 11 % yield. An analogous 39-membered macrocycle produced no rotaxane products under similar conditions. The constitutions of the [4]rotaxanes were determined by NMR spectroscopy and mass spectrometry. Doubly-threaded [3]rotaxanes were also obtained from the reactions but no [2]rotaxanes were isolated, suggesting that upon demetallation the axle of a singly-threaded rotaxane can slip through a macrocycle that is sufficiently large to accommodate three threads

Neuromuscular synaptic function in mice lacking major subsets of gangliosides

Gangliosides are a family of sialylated glycosphingolipids enriched in the outer leaflet of neuronal membranes, in particular at synapses. Therefore, they have been hypothesized to play a functional role in synaptic transmission. We have measured in detail the electrophysiological parameters of synaptic transmission at the neuromuscular junction (NMJ) ex vivo of a GD3-synthase knockout mouse, expressing only the O- and a-series gangliosides, as well as of a GM2/GD2-synthase*GD3-synthase double-knockout (dKO) mouse, lacking all gangliosides except GM3. No major synaptic deficits were found in either null-mutant. However, some extra degree of rundown of acetylcholine release at high intensity use was present at the dKO NMJ and a temperature-specific increase in acetylcholine release at 35 °C was observed in GD3-synthase knockout NMJs, compared with wild-type. These results indicate that synaptic transmission at the NMJ is not crucially dependent on the particular presence of most ganglioside family members and remains largely intact in the sole presence of GM3 ganglioside. Rather, presynaptic gangliosides appear to play a modulating role in temperature- and use-dependent fine-tuning of transmitter output