A port-Hamiltonian framework for displacement-based and rigid formation control

This thesis is devoted to passivity-based formation control for multi-agent systems. Generally, it aims to establish a port-Hamiltonian framework for the problems related to distributed formation control of multi-agent systems. Regarding the constraints of the formations, the displacement-based formation which is based on consensus theory, and rigid formations whose desired shapes are defined by distance, bearing, angle, or combinations of them are considered. Regarding the control objectives, formation stabilization and some maneuvers, such as velocity tracking, orientation, and scale control are investigated. Concerning the system dynamics, in addition to the double integrators with damping terms, the wheeled robot with nonholonomic constraints is also considered

Spectral properties of photon pairs generated by spontaneous four wave mixing in inhomogeneous photonic crystal fibers

The photonic crystal fiber (PCF) is one of the excellent media for generating photon pairs via spontaneous four wave mixing. Here we study how the inhomogeneity of PCFs affect the spectral properties of photon pairs from both the theoretical and experimental aspects. The theoretical model shows that the photon pairs born in different place of the inhomogeneous PCF are coherently superposed, and a modulation in the broadened spectrum of phase matching function will appear, which prevents the realization of spectral factorable photon pairs. In particular, the inhomogeneity induced modulation can be examined by measuring the spectrum of individual signal or idler field when the asymmetric group velocity matching is approximately fulfilled. Our experiments are performed by tailoring the spectrum of pulsed pump to satisfy the specified phase matching condition. The observed spectra of individual signal photons, which are produced from different segments of the 1.9 m inhomogeneous PCF, agree with the theoretical predictions. The investigations are not only useful for fiber based quantum state engineering, but also provide a dependable method to test the homogeneity of PCF.Comment: to appear in Phys. Rev.

Network target for screening synergistic drug combinations with application to traditional Chinese medicine

<p>Abstract</p> <p>Background</p> <p>Multicomponent therapeutics offer bright prospects for the control of complex diseases in a synergistic manner. However, finding ways to screen the synergistic combinations from numerous pharmacological agents is still an ongoing challenge.</p> <p>Results</p> <p>In this work, we proposed for the first time a “network target”-based paradigm instead of the traditional "single target"-based paradigm for virtual screening and established an algorithm termed NIMS (Network target-based Identification of Multicomponent Synergy) to prioritize synergistic agent combinations in a high throughput way. NIMS treats a disease-specific biological network as a therapeutic target and assumes that the relationship among agents can be transferred to network interactions among the molecular level entities (targets or responsive gene products) of agents. Then, two parameters in NIMS, Topology Score and Agent Score, are created to evaluate the synergistic relationship between each given agent combinations. Taking the empirical multicomponent system traditional Chinese medicine (TCM) as an illustrative case, we applied NIMS to prioritize synergistic agent pairs from 63 agents on a pathological process instanced by angiogenesis. The NIMS outputs can not only recover five known synergistic agent pairs, but also obtain experimental verification for synergistic candidates combined with, for example, a herbal ingredient Sinomenine, which outperforms the meet/min method. The robustness of NIMS was also showed regarding the background networks, agent genes and topological parameters, respectively. Finally, we characterized the potential mechanisms of multicomponent synergy from a network target perspective.</p> <p>Conclusions</p> <p>NIMS is a first-step computational approach towards identification of synergistic drug combinations at the molecular level. The network target-based approaches may adjust current virtual screen mode and provide a systematic paradigm for facilitating the development of multicomponent therapeutics as well as the modernization of TCM.</p

Efficiently Disassemble-and-Pack for Mechanism

In this paper, we present a disassemble-and-pack approach for a mechanism to seek a box which contains total mechanical parts with high space utilization. Its key feature is that mechanism contains not only geometric shapes but also internal motion structures which can be calculated to adjust geometric shapes of the mechanical parts. Our system consists of two steps: disassemble mechanical object into a group set and pack them within a box efficiently. The first step is to create a hierarchy of possible group set of parts which is generated by disconnecting the selected joints and adjust motion structures of parts in groups. The aim of this step is seeking total minimum volume of each group. The second step is to exploit the hierarchy based on breadth-first-search to obtain a group set. Every group in the set is inserted into specified box from maximum volume to minimum based on our packing strategy. Until an approximated result with satisfied efficiency is accepted, our approach finish exploiting the hierarchy.Comment: 2 pages, 2 figure

Isolation, characterization and adhesion performance of sorghum, canola and camelina proteins

Doctor of PhilosophyDepartment of Biological and Agricultural EngineeringDonghai WangSorghum distillers dried grains with solubles (DDGS), canola and camelina meals are the main co-products resulting from grain-based ethanol or oil production. The main objective of this research was to study physicochemical properties of proteins isolated from DDGS, canola and camelina meals and their adhesion performance. Acetic acid-extracted sorghum protein (PI) from DDGS had superior adhesion performance in terms of dry, wet and soak adhesion strength compared to acetic acid-extracted sorghum protein (PF) from sorghum flour and aqueous ethanol-extracted sorghum protein (PII) from DDGS. PI had a significantly higher wet strength (3.15 MPa) than PII (2.17 MPa), PF (2.59 MPa), and soy protein without modification (1.63 MPa). The high content of hydrophobic amino acids in PI (57%) was likely the key factor responsible for high water resistance. Canola protein was extracted from canola meal and modified with different concentrations of NaHSO3 (0 to 15 g/L) during protein isolation. Unmodified canola protein showed the highest wet shear strength of 3.97 MPa cured at 190 °C. Adhesion strength of canola protein fractions extracted at pH 5.5 and pH 3.5 (3.9-4.1 MPa) was higher than the fraction extracted at pH 7.0. NaHSO3 slightly weakened adhesion performance of canola protein; however, it improved handling and flow-ability due to breaking of disulfide bonds in proteins. Albumin, globulin, and glutelins were isolated from camelina meal. Adhesion performance of globulin fraction behaved better than glutelin fraction. The greatest wet shear strength of globulin was 3.3 MPa at curing a temperature of 190 °C. Glutelin had a more protein aggregation compared with globulin, as indicated by higher crystallinity and thermal stability, and dense protein aggregate. This compact structure of glutelins may partially contribute to lower adhesion strength as compared to globulin

Adhesive performance of camelina protein affected by extraction conditions

Citation: Qi, G., Li, N., Sun, X. S., & Wang, D. (2016). Adhesive performance of camelina protein affected by extraction conditions. Transactions of the Asabe, 59(3), 1083-1090. doi:10.13031/trans.59.11686Camelina protein (CP) adhesives were prepared from de-hulled camelina meal using alkaline solubilization (CP 8, CP 9, CP 10, CP 11, CP 12) and isolelectric precipitation. CP 12 had the highest protein yield with 46.22%, more than twice that of CP 8 (22.71%), indicating that extreme alkaline pH is necessary for high camelina protein solubility and protein yield. Extreme alkalinization resulted in severe molecular dissociation of camelina protein, as indicated by the appearance of a low molecular weight band (20 kDa). Compared to CP 8, CP 9, CP 10, and CP 11, CP 12 had a completely denatured protein structure with greater amounts of exposed functional groups, which is beneficial to the adhesion strength of CP 12. CP 12 with 9% sodium chloride treatment demonstrated optimum adhesion performance with dry and wet strengths of 4.36 and 1.36 MPa, respectively, compared to 3.37 and 1.05 MPa for CP 12 without sodium chloride treatment. © 2016 American Society of Agricultural and Biological Engineers