Particle Filter for Targets Tracking with Motion Model

Real-time robust tracking for multiple non-rigid objects is a challenging task in computer vision research. In recent years, stochastic sampling based particle filter has been widely used to describe the complicated target features of image sequence. In this paper, non-parametric density estimation and particle filter techniques are employed to model the background and track the object. Color feature and motion model of the target are extracted and used as key features in the tracking step, in order to adapt to multiple variations in the scene, such as background clutters, object's scale change and partial overlap of different targets. The paper also presents the experimental result on the robustness and effectiveness of the proposed method in a number of outdoor and indoor visual surveillance scenes.published_or_final_versio

A nature-derived, flexible and three dimensional (3D) nano-composite for chronic wounds pH monitoring

Current technologies on conductive carbon aerogels are merely for application of super-capacitors, anodes of lithium ion batteries and electrocatalysts. To our best knowledge, carbon nanofibre (CNF) aerogels in biomedical application of chronic wound monitoring have not been reported yet. In this paper, we proposed a chronic wounds pH sensor, which is based on 3D free-standing conductive CNF aerogel derived from pyrolyzed bacterial cellulose (p-BC) as conducting substrate and it is incorporated with flexible and proton-selective PDMS/PANI composite. The resulted p-BC/PDMS/PANI nanocomposite is soft, flexible, and can exhibit near Nernst limit pH sensitivity (~−50.4 mV/pH) in pH buffer solution, and −29 mV/pH in in vitro simulated wound fluid. This renders its applications in flexible bio-sensors and smart wound dressings

Spider silk binder for Si-based anode in lithium-ion batteries

Silicon (Si) has attracted attention for use in lithium ion batteries due to its high theoretical capacity and its natural abundance. However, significant change in the volume of Si electrodes during repeated cycles causes dramatic capacity degradation and reduces the benefits of its attractive qualities. Here, it is reported for the first time that a derivative of natural spider silk is effective for retaining the capacity and decreasing the volume expansion of Si for use in Li-ion batteries as electrodes. Relative to the Si-electrode with polyvinylidene fluoride (SPVDF), the Si-electrode containing binder with the dissolved spider silk (SWS) cells achieved significant enhanced capacities with cycling stability during repeated cycles. The SWS electrode at 250 mA g −1 showed the discharge/charge capacities of 3642/1938 mAh g−1 at 1st cycle, 1789/1541 mAh g−1 at 2nd cycle and then reduced to 1142/1054 mAh g−1 at the 5th cycle. However, the capacities of the SPVDF electrode were 3903/2694 mAh g−1, 1455/1211 mAh g−1, and 458/435 mAh g−1. Furthermore, the discharge capacity of SWS was 333 mAh g−1 at the 38th cycle, but that of SPVDF showed 323 mAh g−1 at the 7th cycle. Such superior performance with good cycling ability may be attributed to the unique properties of spider silk: the folded crystal layer with semi-amorphous structure, the superior properties of viscosity and adhesion, and the close stacking by the protein blocks as well as the side chain R-group of crystal β-sheet. The combination of these characteristics was able to restrain the deleterious change in the volume of Si materials substantially, and to provide superior electrochemical characteristics of lithium ions

Integration of an aerosol-assisted deposition technique for the deposition of functional biomaterials applied to the fabrication of miniaturised Ion sensors

Ion-selective electrodes are at the forefront of research nowadays, with applications in healthcare, agriculture and water quality analysis among others. Despite multiple attempts of miniaturization of these polyvinyl chloride (PVC) gel-based ion sensors, no ion-sensing devices with a thickness below the micrometer range, and operating using open circuit potential, have been developed so far. This work reports the causes of this thickness limitation in potassium-selective sensors. Highly homogeneous ion-sensing films were fabricated by a method based on aerosol assisted chemical vapour deposition, leading to smooth surfaces with 27 ± 11 nm of roughness. Such homogeneity allowed the systematic study of the performance and ionic diffusion properties of the sensing films at sub-micrometer scales. Sensitivities below the Nernst response were found at low thicknesses. The nature of this reduction in sensitivity was studied, and a difference in the superficial and bulk compositions of the films was measured. An optimal configuration was found at 15 µm, with a good selectivity against Na+ (KK+, Na+ = −1.8) a limit of detection in the range of 10−4 M and esponse time below 40 s. The stability of sensors was improved by the deposition of protective layers, which expanded the lifespan of the ion sensors up to 5 weeks while preserving the Nernst sensitivity

Effect of Sodium Treatment on the Performance of Electrostatic Spray Assisted Vapour Deposited Copper-poor Cu(In,Ga)(S,Se)2 Solar Cells

In our work, eco-friendly, non-vacuum and low cost Electrostatic Spray Assisted Vapour Deposition (ESAVD) method has been used to produce Cu(In,Ga)(S,Se) 2 (CIGS) solar cells. Copper (Cu) deficient (Cu/In + Ga = 0.76) CIGS films were designed to avoid the rather dangerous KCN treatment step for the removal of conductive minor phases of Cu 2 S/Cu 2 Se. A simple sodium (Na) treatment method was used to modify the morphology and electronic properties of the absorber and it clearly improved the solar cell performance. The SEM and XRD results testified a slightly increase of the grain size and (112) crystal orientation in the Na-incorporated CIGS thin films. From the Mott-schottky results, it can be seen that the functions of the Na treatment in our non-vacuum deposited CIGS are mainly used for defect passivation and reduction of charge recombination. Photovoltaic characteristics and j-V curve demonstrated that the dipping of CIGS films in 0.2 M NaCl solution for 20 minutes followed by selenization at 550 °C under selenium vapor resulted in the optimum photovoltaic performance, with j sc , V oc , FF and η of the optimized solar cell of 29.30 mA cm -2 , 0.564 V, 65.59% and 10.83%, respectively

Ecofriendly and Nonvacuum Electrostatic Spray-Assisted Vapor Deposition of Cu(In,Ga)(S,Se)2 Thin Film Solar Cells

Chalcopyrite Cu(In,Ga)(S,Se)2 (CIGSSe) thin films have been deposited by a novel, nonvacuum, and cost-effective electrostatic spray-assisted vapor deposition (ESAVD) method. The generation of a fine aerosol of precursor solution, and their controlled deposition onto a molybdenum substrate, results in adherent, dense, and uniform Cu(In,Ga)S2 (CIGS) films. This is an essential tool to keep the interfacial area of thin film solar cells to a minimum value for efficient charge separation as it helps to achieve the desired surface smoothness uniformity for subsequent cadmium sulfide and window layer deposition. This nonvacuum aerosol based approach for making the CIGSSe film uses environmentally benign precursor solution, and it is cheaper for producing solar cells than that of the vacuum-based thin film solar technology. An optimized CIGSSe thin film solar cell with a device configuration of molybdenum-coated soda-lime glass substrate/CIGSSe/CdS/i-ZnO/AZO shows the photovoltaic (j-V) characteristics of Voc = 0.518 V, jsc = 28.79 mA cm(-2), fill factor = 64.02%, and a promising power conversion efficiency of η = 9.55% under simulated AM 1.5 100 mW cm(-2) illuminations, without the use of an antireflection layer. This demonstrates the potential of ESAVD deposition as a promising alternative approach for making thin film CIGSSe solar cells at a lower cost

Piezoelectric and pyroelectric properties of PZT/P (VDF-TrFE) composites with constituent phases poled in parallel or anti-parallel directions

2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Boron nitride enhanced polymer/salt hybrid electrolytes for all-solid-state lithium ion batteries

Solid state polymer electrolyte is a promising candidate for the next generation of all-solid-state lithium ion batteries due to its advantages of light weight, high stability to electrodes, non-flammable, sufficient mechanical strength to prevent lithium dendrite growth, and low cost. Here, through a facile and cost-effective route, two dimensional boron nitride (BN) is applied as an efficient additive in a polymer/salt hybrid electrolyte, which brings about high ionic conductivity, improved mechanical strength and intimate interfacial contact between the electrolyte and electrodes. A 1% BN addition into polymer/salt hybrid electrolyte membrane exhibits a high conductivity of 1.82 × 10−3 S/cm at room temperature. Indentation test shows the BN modified hybrid electrolyte possesses an enhanced hardness (4.99 MPa) and Young's modulus (0.133 GPa). The 1% BN modified hybrid electrolyte is demonstrated to effectively suppress the lithium dendrite growth during repeated striping and plating of lithium. As a result, the battery of lithium metal anode paired with LiFePO_{4} cathode and using the as-fabricated 1% BN enhanced polymer/salt hybrid electrolyte exhibits improved cycling performance with high Coulombic efficiency (over 98%)

Boron Nitride Enhanced Garnet-Type (Li6.25Al0.25La3Zr2O12) Ceramic Electrolyte for an All-Solid-State Lithium-Ion Battery

Solid-state electrolytes (SSEs) are expected to improve not only the safety but also the energy density of lithium-ion batteries, especially referring to the application of most promising Li metal anode which encounters deleterious dendritic growth. The key challenge for the SSEs is the pursuit of higher ionic conductivity, higher mechanical strength, and better chemical and electrochemical stability. Herein, for the first time, hexagonal boron nitride (BN) is employed as the effective additive for garnet-type Li6.25Al0.25La3Zr2O12 (LALZO) SSE during sintering, which induces comprehensively improved properties. Compared with the LALZO electrolyte without BN, a small percentage of 1 wt % BN added to the LALZO electrolyte exhibits 30 times higher ionic conductivity (6.21 × 10–5 S cm–1), 6.6 times higher surface hardness (∼0.5 GPa), and 6.3 times higher reduced modulus (5.6 GPa), much improved chemical stability against air (anti-Li2CO3), and electrochemical stability during lithium stripping/plating at different current densities. As a result, the all-solid-state lithium-ion battery composed of lithium metal anode and LiCoO2 cathode with the 1 wt % BN enhanced LALZO electrolyte delivers a discharge capacity of 120 mA h g–1 and a much higher capacity retention (67% vs 33%) after 50 cycles at a rate of 0.1C than that without BN addition. This BN enhanced garnet-type ceramic electrolyte may provide a facile and efficient approach to further promote the solid-state electrolyte for next-generation high performance energy storage devices

Bioactive coatings

From traditional approaches of employing bulk materials to the new generation of bioactive coated implants, the design of such medical tools is being directed towards the implementation bioactive compounds to allow the direct bonding of living tissues and osteoconduction. However, the development of an optimal bioactive implant for tissue regeneration has not been achieved. The research for novel materials is hindered by the biocompatibility and bioactivity of the compound as well as their mechanical properties. To improve the bioactivity of the implants, the increase of surface area of the implant as well as the use of resorbable compounds is being studied with promising results. Among all different materials and composite employed, the common materials include calcium phosphates and resorbable bioglasses inspired in natural scaffold composition of bones and teeth. In some cases, this material is being used as a coating and combined with further treatments and functional coatings which may reinforce its bioresponsive properties, and in some cases, it can provide additional properties such as antimicrobial activity. In addition, a specific class of bioactive coatings based on biodegradable polymers has also been developed. These coatings temporally aim at accelerating wound healing and forming new tissue at the material-tissue interface around implanted devices or protecting those implants against biomaterial-associated infections. Bioactive, degradable coatings can be generated both from natural and synthetic polymers. Common strategies, reviewed here, are based on natural polymers like proteins, polysaccharides, or glycosaminoglycanes to improve their bioactivity either by chemical functionalization of the biopolymer itself (e.g. introduction of bioactive groups) or by immobilization of bioactive components (e.g. cell adhesion peptides). Degradable or at least water-soluble synthetic polymers as polylactones or polyethylene glycols have been used for long time to create carrier materials for bioactive agents. As exemplary illustrated, those polymers are also used creating either substrate-adhering nanofilms or hydrogel-based thick coatings with high bioactivity to stimulate cell adhesion or avoid microbial adhesion. This chapter aims to summarize all recent approaches in the development of various bioactive coating materials, as well as the coating techniques and further treatment, functionalization and surface modification