Exploring a Quality of Service (QoS) Mechanism to Enhance Multimedia Database Query Processing in Wireless Mobile Environments.

Among the challenges of multimedia computing and mobile computing, a mechanism for data retrieval in multimedia databases under wireless mobile environments seems to be the most difficult issue. The problem is that sizes of images in a multimedia DBMS queried by mobile clients through wireless networks are different and unpredictable. Current Quality of Service (QoS) framework has no answer for it because all the QoS principles are based on users’ pre-requirements. However, the issue is that in multimedia applications, it is difficult to know the size of targeted retrieval object. There should be new mechanism of QoS to participate in query processing and provide an efficient theme around which mobile multimedia database applications can b practicably realized. In this thesis we focus on extending QoS management in wireless mobile environments to specify a range of acceptable QoS for multimedia query processing rather than trying either to guarantee specific values or to stop the querying. Through the investigation of current research approaches, we conclude that the statistical or empirical resource utilizations in query processing are the dominant methods to solve the problems. All proposals choose stopping query if the required QoS conditions can not meet the related statistical or empirical resources utilizations. To address QoS in mobile multimedia DBMS issues, we explore an approach to execute query processing based on real time QoS conditions all coming from client, network, and server. We propose a QoS-based matrix to support query processing of object-relational multimedia databases in the context of wireless mobile environments. The proposed QoS-based Querying Processing Precision Matrix (QQPPM) is based on (1) real-time QoS conditions in wireless networks; (2) multimedia database’s object properties; and (3) Mobile client-site data processing capability. We study related technologies as the foundations to support multimedia query processing in wireless mobile environments. Moreover, we conduct OPNET simulations, and the results indicate that our assumption is reasonable and practicable

Myotis bechsteinii, Bechsteins fladdermus

Hydrated polyelectrolyte (PE) complexes and multilayers undergo a well-defined thermal transition that bears resemblance to a glass transition. By combining molecular simulations and differential scanning calorimetry (DSC) of poly­(diallyldimethylammonium) (PDAC) and poly­(styrenesulfonate) (PSS) multilayers, we establish for the first time that dehydration drives the thermally induced change in plasticization of the complex and in the diffusion behavior of its components. DSC experiments show that the thermal transition appears when the assemblies are hydrated in water but not in the presence of alcohols, which supports that water is required for this transition. These findings connect PE complexes more generally to thermoresponsive polymers and liquid crystal phases, which bear phase transitions driven by the (de)­hydration of functional groups, thus forming a fundamental link toward an integrated understanding of the thermal response of molecular materials in aqueous environments

APSO: An A*-PSO Hybrid Algorithm for Mobile Robot Path Planning

Aiming at the problems of the A* algorithm in mobile robot path planning, such as multiple nodes, low path accuracy, long running time and difficult path initialization of particle swarm optimization, an APSO algorithm combining A* and PSO was proposed to calculate the optimal path. First, a redundant point removal strategy is adopted to preliminarily optimize the path planned by the A* algorithm and obtain the set of key nodes. Second, a stochastic inertia weight is proposed to improve the search ability of PSO. Third, a stochastic opposition-based learning strategy is proposed to further improve the search ability of PSO. Fourth, the global path is obtained by using the improved PSO to optimize the set of key nodes. Fifth, a motion time objective function that is more in line with the actual motion requirements of the mobile robot is used to evaluate the algorithm. The simulation results of path planning show that the path planned by APSO not only reduces the running time of the mobile robot by 17.35%, 14.84%, 15.31%, 15.21%, 18.97%, 15.70% compared with the A* algorithm in the six environment maps but also outperforms other path planning algorithms to varying degrees. Therefore, the proposed APSO is more in line with the actual movement of the mobile robot

Hydration and Temperature Response of Water Mobility in Poly(diallyldimethylammonium)-Poly(sodium 4-styrenesulfonate) Complexes

The combination of all-atom molecular dynamics simulations with differential scanning calorimetry (DSC) has been exploited to investigate the influence of temperature and hydration on the water distribution and mobility in poly(diallyldimethylammonium) (PDADMA) and poly(sodium 4-styrenesulfonate) (PSS) complexes. The findings show that the vast majority of the water molecules hydrating the polyelectrolyte complexes (PECs) with 18-30 wt % hydration are effectively immobilized due to the strong interactions between the PE charge groups and water. Temperature and hydration were found to decrease similarly the fraction of strongly bound water. Additionally, at low hydration or at low temperatures, water motions become dominantly local vibrations and rotations instead of translational motion; translation dominance is recovered in a similar fashion by increase of both temperature and hydration. DSC experiments corroborate the simulation findings by showing that nonfreezing, bound water dominates in hydrated PECs atcomparable hydrations. Our results raise attention to water as an equal variable to temperature in the design and engineering of stimuli-responsive polyelectrolyte materials and provide mechanistic explanation for the similarity.Peer reviewe

Layer-by-Layer Assembly and Electrochemical Study of Alizarin Red S-Based Thin Films

Electroactive organic dyes incorporated in layer-by-layer (LbL) assemblies are of great interest for a variety of applications. In this paper, Alizarin Red S (ARS), an electroactive anthraquinone dye, is employed to construct LbL (BPEI/ARS)n films with branched poly(ethylene imine) (BPEI) as the complementary polymer. Unconventional LbL methods, including co-adsorption of ARS and poly(4-styrene sulfonate) (PSS) with BPEI to assemble (BPEI/(ARS+PSS))n, as well as pre-complexation of ARS with BPEI and further assembly with PSS to fabricate ((BPEI+ARS)/PSS)n, are designed for investigation and comparison. Film growth patterns, UV–Vis spectra and surface morphology of the three types of LbL assemblies are measured and compared to reveal the formation mechanism of the LbL films. Electrochemical properties including cyclic voltammetry and spectroelectrochemistry of (BPEI/ARS)120, (BPEI/(ARS+PSS))120 and ((BPEI+ARS)/PSS)120 films are studied, and the results show a slight color change due to the redox reaction of ARS. ((BPEI+ARS)/PSS)120 shows the best stability among the three samples. It is concluded that the manner of dye- incorporation has a great effect on the electrochemical properties of the resultant films

Effect of Water on the Thermal Transition Observed in Poly(allylamine hydrochloride)–Poly(acrylic acid) Complexes

Here, we present the thermal behavior of polyelectrolyte complexes (PECs) containing weak polyelectrolytes poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) as influenced by water content and complexation pH. Modulated differential scanning calorimetry (MDSC) reveals a glass-transition-like thermal transition (Ttr) that decreases in value with increasing hydration and with decreasing complexation pH. We show the collapse of all Ttr values into a single master curve when plotted against the ratio of water molecules per intrinsic (PAH+-PAA-) ion pair for all pH values explored. Remarkably, this master curve is linear when the natural log of the water to intrinsic ion pair ratio is plotted against the inverse of Ttr. This strongly indicates that the thermal transition is heavily influenced by water at the intrinsic ion pair site. Other water-solvent mixtures are also explored, for which Ttr appears to depend only on water content, regardless of the added solvent. These results suggest that water plays a dual role in PAH-PAA complex: first by participating in the hydrogen-bonding network within and second by plasticizing the PEC. A hypothesis for the thermal transition is proposed in which hydrated PECs undergo a two-step thermal transition caused by an initial restructuring of the water-polyelectrolyte hydrogen-bonding network, followed by chain relaxation.Peer reviewe

The influence of ionic strength and mixing ratio on the colloidal stability of PDAC/PSS polyelectrolyte complexes

Polyelectrolyte complexes (PECs) form by mixing polycation and polyanion solutions together, and have been explored for a variety of applications. One challenge for PEC processing and application is that under certain conditions the as-formed PECs aggregate and precipitate out of suspension over the course of minutes to days. This aggregation is governed by several factors such as electrostatic repulsion, van der Waals attractions, and hydrophobic interactions. In this work, we explore the boundary between colloidally stable and unstable complexes as it is influenced by polycation/polyanion mixing ratio and ionic strength. The polymers examined are poly(diallyldimethylammonium chloride) (PDAC) and poly(sodium 4-styrenesulfonate) (PSS). Physical properties such as turbidity, hydrodynamic size, and zeta potential are investigated upon complex formation. We also perform detailed molecular dynamics simulations to examine the structure and effective charge distribution of the PECs at varying mixing ratios and saltconcentrations to support the experimental findings. The results suggest that the colloidally stable/unstable boundary possibly marks the screening effects from added salt, resulting in weakly charged complexes that aggregate. At higher salt concentrations, the complexes initially form and then gradually dissolve into solution.Peer reviewe