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As new structural and functional materials, porous materials have unparalleled advantages compared to dense materials because of their special pore structure. The powder metallurgy technique was utilized to prepare titanium foams by adding space holders to generate pores and FeV80 to modify the structure and properties of the materials. The results show that the TixVy (x + y = 1) phase exists in the sintering product after adding FeV80 powder. The content of FeV80 increases from 0% to 12%, resulting in the initial yield strength increasing from 190.08 MPa to 380.82 MPa; when the content of FeV80 is increased to 16%, the initial yield strength decreases to 331.77 MPa. Therefore, the improvement created in the mechanical properties of the porous titanium by adding ferrovanadium alloy is highly significant.

Endoscopic magnetoacoustic tomography with magnetic induction (EMAT-MI) provides an interventional tool to detect the electrical conductivity distribution of a tubular structure with high spatial resolution. In this work, a preliminary study on the numerical simulation of EMAT-MI images was conducted. The magnetic excitation, generation and propagation of magnetoacoustic (MA) waves in the multi-layered wall tissues were modeled and numerically simulated. The cross-sectional distribution of the acoustic source and electrical conductivity was recovered from the acoustic pressure series based on time-reversal. The validity has been demonstrated on two computer-generated phantoms. Results suggested that the conductivity boundaries can be clearly distinguished in the images of acoustic-source or conductivity distribution which are highly consistent with the numerical simulation. The resolution of the MA signals excited by the Lorentz force divergence is closely related to the pulse width of the excitation current. Sparse measuring locations and limited-view scanning may reduce the image quality although higher SNR of the MA signals leads to better image reconstruction.

The decomposition of limestone in converter slag directly determines the speed of slag melting for lime that has a strong effect on the steelmaking process of the converter. In this paper, a high temperature furnace was used to study the decomposition behavior of cylindrical limestone samples in the converter early slag at the temperatures of 1250 °C, 1300 °C, and 1350 °C under laboratory conditions, and macro-dynamics equation was used to determine the rate-determining step for limestone decomposition in the converter early slag. The results show that when the limestone is decomposed in the early converter slag, the heat transfer from the slag through the lime layer to the unreacted core is the rate-determining step. The limestone decomposition rate in converter slag is slightly lower than that in hot metal. Finally, the suitable grain size of the limestone added into the converter was determined. Thus, this study provides theoretical guidelines for practical use of converter steelmaking in industrial production.

The cathode material LiNi 0.5 Mn 0.5- x Cr x O 2 ( x =0, 0.01, 0.02, 0.05, 0.1) was synthesized via a low temperature combustion process. The influence of the partial substitution of Cr for Mn on its electrochemical performance was investigated. Charge/discharge test results show that the partial substitution of Cr for Mn has a significant influence on the electrochemical performance of LiNi 0.5 Mn 0.5- x Cr x O 2 , and the proper amount substitution of Cr for Mn ( x =0.02) can increase its discharge capacity and improve its cyclic stability. The X-ray diffraction (XRD) and Cycle Voltammetry (CV) analyses indicate that the proper amount substitution of Cr for Mn can suppress the cation mixing in the cathode material, reduce the electrochemical polarization of the electrode material and improve its reversibility. The discharge capacity of LiNi 0.5 Mn 0.48 Cr 0.02 O 2 at 0.1 C between 2.5 and 4.6 V is 179.9 and 171.0 mAh/g in the 1st and the 50th cycle, respectively, with a capacity retention of 95.1%.

The advantage of Carbon Fiber Reinforced Polymer (CFRP) is obvious as a common space material for low density, low thermal expansion coefficient and high specific stiffness characteristics, it is the ideal material choice for space optical reflector. Mirror structure with honeycomb can achieve high rates of lightweight, as well as high specific stiffness. For Φ300mm CFRP mirror, accounting of the actual process properties of CFRP, mirror panels laminated based on thermal stability design, honeycomb fabricated using one innovative inlaying-grafting design method. Finally, lightweight structure design of the CFRP primary mirror completed, the thermal stability result of the Φ300mm CFRP mirror achieved is 10nm°C.

Computer-generated hologram (CGH) is an effective way to compensate wavefront aberration in null test of aspheric surfaces and freeform surfaces. Our strategies of CGH design for 600mm diameter SiC primary mirror surface figure testing are presented, and an experiment demonstrating the compensation test results of CGH is reported. We design a CGH including two sections on the same substrate in order to align the CGH to the incident wavefront: main section for compensating wavefront in null test, alignment section for adjusting the relative position between CGH and interferometer. In order to isolate different orders of diffraction, we used power carrier to make different orders of diffraction come to focus at different position along the axis to avoid ghost reflections. We measured the 600mm diameter SiC primary mirror using this CGH, and the surface test result is 0.033λ rms.

A two-phase shifting method is introduced to eliminate the strong autocorrelation noise inherent in spectral optical coherence tomography and to mitigate the unwanted auto- and cross-coherent terms introduced by the reflections from various optical interfaces present in the system. Furthermore, this method is also able to amplify the desired signal by a factor of 2. The feasibility of such a method is demonstrated using a mirror-like object. An intact porcine cornea tissue in vitro is also used to show the potential of this method for biological imaging.

Electroluminescence (EL) is observed from the Au/Si-rich SiO2 film/p-Si diodes, in which the Si-rich SiO2 films are scored deliberately by a diamond tip. The EL intensity of the scored diode annealed at 800 degreesC is about 6 times of that of the unscored counterpart. The EL spectrum of the unscored diode could be decomposed into two Gaussian luminescence bands with peaks at about 1.83 and 2.23eV, while for the EL spectrum of the scored diode, an additional Gaussian band at about 3.0eV appears, and the 1.83-eV peak increases significantly in intensity. The photoluminescence (PL) spectrum of an unscored Si-rich SiO2 film has only one band peaking at about 1.48eV, whereas the PL spectrum of the scored one has two bands at about 1.48 and 1.97eV. We consider that the high-density defect regions produced by the scoring provide new luminescence centres and become some types of nonradiative centres in the Si oxide layer, which thus result in changes of the EL and PL spectra.

Topical medication remains the first line treatment of glaucoma; however, sustained ocular drug delivery via topical administration is difficult to achieve. Most drugs have poor penetration due to the multiple physiological barriers of the eye and are rapidly cleared if applied topically. Currently, daily topical administration for lowering the intra-ocular pressure (IOP), has many limitations, such as poor patient compliance and ocular allergy from repeated drug administration. Poor compliance leads to suboptimal control of IOP and disease progression with eventual blindness. The delivery of drugs in a sustained manner could provide the patient with a more attractive alternative by providing optimal therapeutic dosing, with minimal local toxicity and inconvenience. To investigate this, we incorporated latanoprost into LUVs (large unilamellar vesicles) derived from the liposome of DPPC (di-palmitoyl-phosphatidyl-choline) by the film hydration technique. Relatively high amounts of drug could be incorporated into this vesicle, and the drug resides predominantly in the bilayer. Vesicle stability monitored by size measurement and DSC (differential scanning calorimetry) analysis showed that formulations with a drug/lipid mole ratio of about 10% have good physical stability during storage and release. This formulation demonstrated sustained release of latanoprost in vitro, and then tested for efficacy in 23 rabbits. Subconjunctival injection and topical eye drop administration of the latanoprost/liposomal formulation were compared with conventional daily administration of latanoprost eye drops. The IOP lowering effect with a single subconjunctival injection was shown to be sustained for up to 50 days, and the extent of IOP lowering was comparable to daily eye drop administration. Toxicity and localized inflammation were not observed in any treatment groups. We believe that this is the first demonstration, in vivo, of sustained delivery to the anterior segment of the eye that is safe and efficacious for 50 days.

With the thermal effects of substrate and package in mind, electrothermal simulations are performed on the transient response of transistors under the injection of electromagnetic pulses by adopting the 2-D device simulator ISE-TCAD. Simulation results show that the junction temperature inside a transistor will increase so instantly to the melting point of silicon within tens or hundreds of nanoseconds as to damage the device when the current mode second breakdown arises in the transistor for electromagnetic pulses with high power. In this case, the thermal resistance of package has little influence over the burnout time and damage energy. However, when the electromagnetic pulse has too small a power to produce the current mode second breakdown, the thermal mode second breakdown will arise in the transistor. In this case, the thermal resistance of package will have a notable effect over the burnout time and damage energy.

The motion of current filaments in avalanching PIN diodes has been investigated in this paper by 2D transient numerical simulations. The simulation results show that the filament can move along the length of the PIN diode back and forth when the self-heating effect is considered. The voltage waveform varies periodically due to the motion of the filament. The filament motion is driven by the temperature gradient in the filament due to the negative temperature dependence of the impact ionization rates. Contrary to the traditional understanding that current filamentation is a potential cause of thermal destruction, it is shown in this paper that the thermally-driven motion of current filaments leads to the homogenization of temperature in the diode and is expected to have a positive influence on the failure threshold of the PIN diode.

A two-dimensional electrothermal model of the bipolar transistor (BJT) is established, and the transient behaviors of the BJT originally in the forward-active region are simulated with the injection of electromagnetic pulse from the base. The results show that the damage location of the BJT shifts with the amplitude of the pulse. With a low pulse amplitude, the burnout of the BJT is caused by the avalanche breakdown of the emitter-base junction, and the damage location lies in the cylindrical region of this junction. With a high pulse amplitude, the damage first occurs at the edge of the base closer to the emitter due to the second breakdown of the p-n-n+ structure composed of the base, the epitaxial layer and the substrate. The burnout time increases with pulse amplitude increasing, while the damage energy changes in a decrease-increase-decrease order with it, thus generating both a minimum value and a maximum value of the damage energy. A comparison between simulation results and experimental ones shows that the transistor model presented in the paper can not only predict the damage location in the BJT under intense electromagnetic pulses, but also obtain the damage energy.

We conduct a theoretical study of the damage susceptibility trend of a typical bipolar transistor induced by a high-power microwave (HPM) as a function of frequency. The dependences of the burnout time and the damage power on the signal frequency are obtained. Studies of the internal damage process and the mechanism of the device are carried out from the variation analysis of the distribution of the electric field, current density, and temperature. The investigation shows that the burnout time linearly depends on the signal frequency. The current density and the electric field at the damage position decrease with increasing frequency. Meanwhile, the temperature elevation occurs in the area between the p–n junction and the n–n+ interface due to the increase of the electric field. Adopting the data analysis software, the relationship between the damage power and frequency is obtained. Moreover, the thickness of the substrate has a significant effect on the burnout time.

This paper presents a theoretical study of the pulse-width effects on the damage process of a typical bipolar transistor caused by high power microwaves (HPMs) through the injection approach. The dependences of the microwave damage power, P, and the absorbed energy, E, required to cause the device failure on the pulse width τ are obtained in the nanosecond region by utilizing the curve fitting method. A comparison of the microwave pulse damage data and the existing dc pulse damage data for the same transistor is carried out. By means of a two-dimensional simulator, ISE-TCAD, the internal damage processes of the device caused by microwave voltage signals and dc pulse voltage signals are analyzed comparatively. The simulation results suggest that the temperature-rising positions of the device induced by the microwaves in the negative and positive half periods are different, while only one hot spot exists under the injection of dc pulses. The results demonstrate that the microwave damage power threshold and the absorbed energy must exceed the dc pulse power threshold and the absorbed energy, respectively. The dc pulse damage data may be useful as a lower bound for microwave pulse damage data.

A novel semicircular electrode metal-semiconductor-metal (SEMSM) ultraviolet detector is modeled, investigated and characterized with a self-consistent numerical calculation method. For the purpose of model and performance verification, a comprehensive comparison of the SEMSM detector and a conventional electrode MSM detector is carried out with experimental data. The results indicate that the physical models are able to predict the enhanced device features. Moreover, the structural parameters have been adjusted appropriately to optimize the SEMSM detector. The findings show that a device with a 2 μm finger radius and 3 μm spacing exhibits outstanding characteristics in terms of a peak responsivity of 0.177 A/W at 290 nm, a maximum external quantum efficiency of over 75%, and a comparable normalized photocurrent to dark current ratio of 1.192 × 1011 W−1 at 0.3 V bias. These results demonstrate that the SEMSM detector has excellent performance for optoelectronic integrated circuit applications.

Based on the device operation mechanism and physical model, effects of the improved hetero-material-gate (HMG) approach on deep sub-micron silicon carbide (SiC) metal-semiconductor field-effect transistor (MESFET) are analyzed. By comparing with the conventional MESFET, it is shown that the improved HMG approach induces a multi-stepped distribution of the potential in the channel, leading to an enhanced electric field at the source. Meanwhile, the position of the maximum of the channel potential is changed to the drain side compared with the dual-material-gate (DMG) device, thus the carriers in the channel are accelerated more efficiently and the variation of potential caused by drain voltage is eliminated to a certain degree, resulting in a better restraint in short-channel effect. Also, different technological parameters are designed to study the dependence of the device performance and an optimization plan is obtained, leading to a decreased sub-threshold swing. In addition, asymmetric gate structures are designed for high power application, achieving an improved distribution of the electric field at the gate edge and an enhanced breakdown voltage of the small scale device.

An improved structure of silicon carbide metal—semiconductor field-effect transistors (MESFET) is proposed for high power microwave applications. Numerical models for the physical and electrical mechanisms of the device are presented, and the static and dynamic electrical performances are analysed. By comparison with the conventional structure, the proposed structure exhibits a superior frequency response while possessing better DC characteristics. A p-type spacer layer, inserted between the oxide and the channel, is shown to suppress the surface trap effect and improve the distribution of the electric field at the gate edge. Meanwhile, a lightly doped n-type buffer layer under the gate reduces depletion in the channel, resulting in an increase in the output current and a reduction in the gate-capacitance. The structural parameter dependences of the device performance are discussed, and an optimized design is obtained. The results show that the maximum saturation current density of 325 mA/mm is yielded, compared with 182 mA/mm for conventional MESFETs under the condition that the breakdown voltage of the proposed MESFET is larger than that of the conventional MESFET, leading to an increase of 79% in the output power density. In addition, improvements of 27% cut-off frequency and 28% maximum oscillation frequency are achieved compared with a conventional MESFET, respectively.

Combining self-heating effect, mobility degradation in high electric field and avalanche generation effect, a two-dimensional electro-thermal model of the typical silicon-based n+-p-n-n+ structure bipolar transistor induced by high power microwave is established in this paper. By analyzing the variations of device internal distributions of the electric field, the current density and the temperature with time, a detailed investigation of the damage effect and the mechanism of the bipolar transistor under the injection of 1GHz equivalent voltage signals from the base and collector is performed. The results show that temperature elevation occurs in the negative half-period and the maximum temperature falls slightly in the positive half-period when the signals are injected from the collector. Compared with the former, device damage occurs easily with the signals injected from the base. Specifically, the base-emitter junction is susceptible to damage. The damage results caused by two large-amplitude signals with initial phases of 0 and respectively indicate that the injected signal with an initial phase of is liable to cause device damage. Meanwhile, the emitter series resistance can enhance the capability of the device to withstand microwave damage effectively.

A study on the influence of the external resistor and the external voltage source during the injection of the electromagnetic pulse (EMP) into the bipolar transistor (BJT) is carried out. Research shows that the increase of the external resistor Rb at base makes the burnout time of the device decrease slightly, the increase of the external voltage source Vbe at base can aid the damage of the device when the magnitude of the injecting voltage is relatively low and has little influence when the magnitude is sufficiently high causing the device appearing the PIN structure damage, and the increase of the external resistor Re can remarkably reduce the voltage drops added to the device and improve the durability of the device. In the final analysis, the effect of the external circuit component on the BJT damage is the influence on the condition which makes the device appear current-mode second breakdown.

A study of the internal damage process and mechanism of the typical n+-p-n-n+ structure bipolar transistor induced by the intense electromagnetic pulse (EMP) is carried out in this paper from the variation analysis of the distribution of the electric field,the current density and the temperature. Research shows that the damage position of the bipolar transistor is different with the different magnitude of the injecting voltage,when the magnitude of the injecting voltage is low the damage will appear firstly near the collector region under the center of the emitter region,and when the magnitude of the injecting voltage is sufficiently high the damage will appear firstly at the edge of the base near the emitter due to the breakdown of the PIN structure composed of the base-epitaxial layer-collector. Adopting the data analysis software,the relation equation between the device damage power P and the pulse width T under different injecting voltage is obtained. Owing to the variety of the device damage energy,it is demonstrated that the empirical formulas of the intense electromagnetic pulse P=AT-1 (A is a constant) is modified to P=AT-1.4 for the bipolar transistor.

Room temperature photoluminescence (PL) has been observed from Er doped silicon rich silicon oxide films grown by magnetron sputtering. For all kinds of silicon rich silicon oxide films grown with different excess Si contents, each PL spectrum has two peaks at 1.54 and 1.38μm, which originate from Er3+ and a certain kind of defects, respectively, in the silicon rich silicon oxide. It was found that 1.54 and 1.38μm PL peak intensities are correlated with each other. The PL intensity-dependence on the excess-Si content and annealing temperature was studied in detail.

The (SiO2/Si/SiO2) nanoscale double-barrier/n+- Si structures with Si layers of various thicknesses were fabricated by the two-t arget alternative magnetron sputtering technique. The thicknesses of the Si laye rs in the structures are from 2nm to 4nm with an interval of 0.2nm. The control samples with Si layers of 0nm were also made. After these structures were anneal ed at 600℃ in a N2 ambient for 30min, electroluminescence (EL) from the Au/SiO2/Si/SiO2/n+-Si structures were obser ved under reverse biases (n+-Si is biased to positive). It was found that the current and EL intensity synchronously swing with increasing Si layer t hickness. All EL spectra of the samples can be decompounded into two Gaussian lu minescent spectra with peaks at 1.85eV (670nm) and 2.26eV (550nm). Analysis of e xperimental results indicates that the EL orginates from the recombination of el ectrons and holes, which are produced in an avalanche process in the Au/(SiO2/Si/SiO2) nanoscale double-barrier/n+-Si structure , via luminescence centers in the SiO2 layers.

Using a Ge-SiO2 (GSO) composite target with the Ge wafer in the target having percentage areas of 0%,5% and 10%,three types of nanometer Ge particles embedded Si oxide films were deposited on p-type Si substrates by the rf magnetron sputtering technique. These samples were annealed in a N2 atmosphere at 300,600,800 or 900℃ for 30min.From Raman scattering spectra,we obtained the sizes of nanometer Ge particles which increase with increasing percentage area of the Ge wafer in the sputtering target.From the fitting of Raman scattering spectra,average diameters of nanometer Ge particles in the GSO(5%) sample increase from 5.4 to 9.5nm with annealing temperature increasing from 600 to 900℃. The peak with energy around 2.1eV exists in the photoluminescence spectra of all the different sizes of nanometer Ge particles embedded silicon oxide samples.The photoluminescence spectrum of the silicon oxide film prepared using a pure SiO2 target has other two peaks with light emission energies around 1.9 and 2.3eV respectively. The experimental facts are inconsistent with the predication of the quantum confinement model,but can be explained by the quantum confinement/luminescence center model.

The structures of Au/Si-rich SiO2/p-Si and Au/Si-rich SiO2/n+-Si have been fabricated and their electroluminescence characteristics have comparatively been studied. For the Au/Si-rich SiO2/p-Si structure, when the forward bias is more than 4V, red light is emitted, while under the reverse bias, no light is observed. For Au/Si-rich SiO2/n+-Si structure, it does not emit light under the forward bias, but it emits red light when the reverse bias is greater than 3.5V. The mechanism for electroluminescence from the Au/Si-rich SiO2/n+-Si structure is disscussed.