一种光、电驱动的生物炭/硬脂酸复合相变材料的制备及其性能

利用农业固体废弃物玉米秸秆为前体,经700℃高温热解、KOH刻蚀后得到了具有三维孔道结构和大比表面积(2136.67m^(2)/g)的生物炭(KBC)。以KBC为载体,利用乙醇溶解、真空浸渍的方式将有机相变材料硬脂酸(SA)注入其内部孔道中,获得了一种生物炭/硬脂酸(KBC/SA)复合相变材料。通过红外光谱(IR)、粉末X射线衍射(XRD)、扫描电镜(SEM)、热重分析(TG)、差示扫描量热分析(DSC)等表征手段,对其组成结构、微观形貌、储热性能以及稳定性进行了研究。结果表明,当SA质量分数为71.2%时,复合相变材料的储热性能最佳,其相变过程中的熔融焓和结晶焓分别为126.3J/g和128.7J/g,且经过100次循环储、放热性能测试后,相变焓值无明显变化。相变过程中无渗漏现象发生,表明KBC/SA是一种性能优异的定形相变材料。此外,KBC/SA复合相变材料具有良好的光热、电热转换能力,能够将太阳光能和电能转化为热能并储存和释放。当被模拟太阳光和直流电(U=5.0V)驱动后,其光热、电热转换效率可分别达到78.3%和70.1%。因此所制备的KBC/SA复合相变材料不仅能作为一种储热材料使用,而且在绿色清洁能源转化利用方面具有潜在价值。

A 1.25Gb/s InP-Based Vertical Monolithic Integration of an MQW Laser Diode and an HBT Driver witha Lateral Buffer Mes a Structure

A novel fabrication process related to a smoothly wet chemical etching profile o f InP-based epitaxial layers in the crystal direction of [01for an InP-based monol ithic vertically integrated transmitter with an MQW laser diode and a heterojunction bipolar tran sistors driver circuit is described.A clear eye output diagram via an O/E converter is demonstrat ed und er a 1.25Gb/s non-return-zero pseudorandom code with a pattern length of 2 the integrated transmitter has a power dissipation of about 120mW with an optical output of 2dBm.

Implementation of a DC-10Mb/s 0.5μm CMOS Laser Diode Driver

A DC-10Mb/s laser diode driver,compatible with TTL and CMOS levels,is presented. The optical power corresponding to‘1＇ and ‘0＇ can be set independently with resistors off-chip and stabilized with a closed loop. A novel peak-to- peak optical power monitor and stabilization mechanism is introduced. The circuit, fabricated in a CSMC 0. 5μm mixed signal CMOS process, can provide 120mA maximum drive current and 0. 6dB extinction ration fluctuation over - 20 ＋ 80℃ ,which is independent of input pattern.

A 16×16 Micro Mirror Array for Optical Switches

This paper reports on the design, fabrication,and performance of a high-reflectivity large-rotation mirror array for MEMS （micro-electro-mechanical system） 16 × 16 optical switches. The mirror in the array can enlarge its rotation an- gles up to 90° and keep a steady state to steer the optical signal. According to the large-rotation behavior, an electro- mechanical model of the mirror is presented. By monolithic integration of fiber grooves and mirrors fabricated by a sur- face and bulk hybrid micromachining process, the coarse passive alignment of fiber-mirror-fiber can be achieved. The re- flectivity of the mirror is measured to be 93.1% ~96.3%. The switches demonstrate that the smallest fiber-mirror-fiber insertion loss is 2. ldB using OptiFocusTM collimating lensed fibers. Moreover,only about ＋- 0.01dB oscillating amplitude of insertion loss is provoked after the device is tested for 15min for 5-90Hz in the vertical vibration amplitude of 3mm.

Laser diode drive method with narrow-width and high-peak current for multi-line LIDAR

Light detection and ranging (LIDAR) based on time of flight (TOF) method is widely used in many fields related to distance measurement. LIDAR generally uses laser diode (LD) to emit the pulsed laser with high peak power and short duration to ensure a large distance measurement range and eye safety. To achieve this goal, we propose a pulsed LD drive method producing the drive current with high peak and narrow pulse width. We analyze the key issues and related theories of the drive current generation based on this method and design an LD driver. A model of drive current generation is established and the influence of operating frequency on drive current is discussed. The LD driver is simulated by software and verified by experiments. The working frequency of the driver changes from 20 kHz to 100 kHz and the charging voltage is set at 130 V. The current produced by this driver has a duration of 8.8 ns and a peak of about 35 A, and the peak output optical power of the LD exceeds 75 W.

Progress of Si-based Optoelectronic Devices

Si-based optoelectronics is becoming a very active research area due to its potential applications to optical communications.One of the major goals of this study is to realize all-Si optoelectronic integrated circuit.This is due to the fact that Si-based optoelectronic technology can be compatible with Si microelectronic technology.If Si-based optoelectronic devices and integrated circuits can be achieved,it will lead to a new informational technological revolution.In the article,the current developments of this exciting field are mainly reviewed in the recent years.The involved contents are the realization of various Si-based optoelectronic devices,such as light-emitting diodes,optical waveguides devices,Si photonic bandgap crystals,and Si laser,etc.Finally,the developed tendency of all-Si optoelectronic integrated technology are predicted in the near future.

Sea urchin‐like NiMoO_(4) nanorod arrays as highly efficient bifunctional catalysts for electrocatalytic/photovoltage‐driven urea electrolysis

Developing multifunctional electrocatalysts with high catalytic activity,longterm stability,and low cost is essential for electrocatalytic energy conversion.Herein,sea urchinlike NiMoO_(4) nanorod arrays grown on nickel foam has been developed as a bifunctional electrocatalyst for urea oxidation and hydrogen evolution.The NiMoO_(4)‐200/NF catalyst exhibits efficient activity toward hydrogen evolution reaction with a low overpotential of only 68 mV in 1.0 mol/L KOH to gain a current density of 10 mA cm^(–2).The NiMoO_(4)‐300/NF catalyst exhibits a prominent oxygen evolution reaction(OER)catalytic activity with an overpotential of 288 mV at 50 mA cm^(–2),as well as for urea oxidation reaction with an ultralow potential of 1.36 V at 10 mA cm^(–2).The observed difference in electrocatalytic activity and selectivity,derived by temperature variation,is ascribed to different lattice oxygen contents.The lattice oxygen of NiMoO_(4)‐300/NF is more than that of NiMoO_(4)‐200/NF,and the lattice oxygen is conducive to the progress of OER.A urea electrolyzer was assembled with Ni‐MoO_(4)‐200/NF and NiMoO_(4)‐300/NF as cathode and anode respectively,delivering a current density of 10 mA cm^(–2)at a cell voltage of merely 1.38 V.The NiMoO_(4)nanorod arrays has also been successfully applied for photovoltage‐driven urea electrolysis and hydrogen production,revealing its great potential for solar‐driven energy conversion.

Bio-solubilization of Chinese lignite II:protein adsorption onto the lignite surface

Lignite bio-solubilization is a promising technology for converting solid lignite into oil.This study concerns the adsorption of lignite-solubilizing enzymes onto the lignite surface.Adsorption capacity, infrared spectral analysis and driving forces analysis are studied as a way to help understand the bio-solubilization mechanism.The results show that the amount of lignite bio-solubilization is proportional to the amount of adsorbed lignite-solubilizing enzymes.An increase in lignite-solubilizing enzyme adsorption of 10% leads to a 7% increase in lignite bio-solubilization.However, limited amounts of enzymes can be adsorbed by the lignite, thus resulting in low percentages of bio-solubilization.Infrared spectral analysis shows that side chains, such as hy-droxyl and carbonyl, of the lignite structure are the main, and necessary, structures where lignite-solubilizing enzymes attachto the lignite.Furthermore, driving force analysis indicates that the electrostatic force between lignite and enzymes is the main adsorption mechanism.The forces are influenced by solution pH levels, the zeta potential of the lignite and the isoelectric points of the en-zymes.

A new dimmer for alternating-current directly driven light-emitting-diode lamp

A new dimmer using a mental-oxide-semiconductor field-effect transistor (MOSFET) for alternating-current (AC) directly driven light-emitting-diode (LED) lamp was presented. The control method of proposed dimmer is pulse width control (PWM) method. Compared with the conventional phase-controlled dimmer, the proposed PWM dimmer can produce sine wave and did not cause harmonics problem. Furthermore, the proposed control method did not amplify the light flicker due to the independence of input voltage. Therefore, the PWM dimmer can be used as the dimmer of the AC LED lamp instead of the conventional phase-controlled dimmer. The experimental result shows that the proposed PWM dimmer has good performances.

Development of Fiber Optically Driven Instrument for High-voltage Line Current

The measurement theorem of fiber optically driven instrument for high-voltage line current is presented. The PLL voltage-frequency-narrow pulse principle and its micro-consumption mechanism are proposed, followed by analysis on the two main factors affecting PLL measurement precision. A software design scheme using 80C196KB micro-controller is introduced. The experiment result is satisfactory.

Numerical Controlled Two Optical Paths CO_2 Laser Die-Cutting Technology

A CO2 laser die-cutting system, which does not need die board any more, is a new technique for manufac-turing packing box. Two optical paths, the galvanometer scanning system and the flying optical system, are used to satisfy different processing needs. The scanning system is composed of galvanometer scanning mirrors and F-θ lens. And the flying optical system is driven by two servo motors. This paper presents the software and hardware design of the laser die-cutting system, the difference between the two optical paths, as well as the relationship among the cutting speed, thickness of wrapping paper and laser power. The cutting speed and thickness of wrapping paper are linearly increased by the incremental laser power, while the cutting speed is hyperbolically decreased by the incremental thickness of wrapping paper when the laser power is constant. The amount of incision is reduced by 20% and the processing time by 40% when tested by a low power RF CO2 laser die-cutting system using the optimized program. This tech- nique is also used for the reference of other rapid laser processing systems.

A MEMS stronglink with multi-try function used for PC startup in authentication system

The stronglink with muhi-try function based on MEMS technology and the PC startup in authentication system have been designed and fabricated. The generation principle and structure of UQS code are introduced, which consists of two groups of metal counter-meshing gears, two pawl/ratchet mechanisms, two driving micromotors and two resetting micromotors. The energy-coupling element is a photoelectric sensor with a circular and notched plate. It is fabricated using the UV-LiGA process and precision mechanical engineering. The PC startup authentication system is controlled by BIOS program, which is written into the chip according with special format. The program in BIOS output signals controls the running of stronglink to finish the process of authentication. The device can run more than 10000 times before a stop. The driving voltage is 12 V, and the normal decoding time is 3 s.

Selective Deflection of Polarized Light Via Coherently Driven Four-Level Atoms in a Double-Λ Configuration

We study the interaction of a weak probe field, having two circular polarized components, i.e., cr- and a＋ polarization, with an optically dense medium of four-level atoms in a double-A configuration, which is mediated by the electromagnetically induced transparency with a polarized control light with spatially inhomogeneous profile. We analyse the deflection of the polarized probe light and we find that we can selectively determine which circular component will be deflected after the polarized probe light enters the atom medium via adjusting the polarization and detuning of the control field.

Strain-induced robust magnetic anisotropy and room temperature magnetoelectric coupling effect in epitaxial SmFeO3 film

Rare-earth orthoferrite SmFeO3 is an outstanding single-phase multiferroic material,holding great potential in novel low-power electronic devices.Nevertheless,simultaneous magnetic and ferroelectric orders as well as magnetoelectric(ME)coupling effect at room temperature(RT)in this system have not been demonstrated yet.In this study,epitaxial SmFeO3 films were successfully prepared onto tensile-strain Nb-SrTiO3(Nb-STO)substrates by a pulsed laser deposition(PLD)method.Measurement results show that the films exhibit obvious ferromagnetic and ferroelectric orders at RT.Meanwhile,the magnetic anisotropy gradually changes from out-of-plane(OP)to in-plane(IP)direction with increasing film thickness,which is attributed to the variations of O 2p-Fe 3d hybridization intensity and Fe 3d-orbit occupancy caused by the strain-relaxed effect.Moreover,electrically driven reversible magnetic switching further proves that the SmFeO3 films exhibit the RT ME coupling effect,suggesting promising applications in new-generation electric-write magnetic-read data storage devices.

Modified Bubble Core Fields and Bubble Shape in Laser Driven Plasma

Bubble core fields as well bubble shape modification due to the nondepleted electrons inside the bubble is investigated theoretically. It is found that the Mope of transverse fields are reduced significantly, however, the slope of longitudinal electric field, which plays a key role on electrons acceleration in bubble, changes little. Moreover a modified longitudinal compressed bubble shape leads to a shorter dephasing distance which makes the electrons acceleration energy reduced to some extent. As a comparison we perform particle-in-cell simulations whose results are consistent with that of our theoretical consideration.

A newly-designed self-powered electrochromic window

By converting incident light into electric power,self-powered electrochromic window(SP-ECW)can achieve color change in electrochromic layer with no need for external voltage.In this work,a newly-de signed SP-ECW is proposed for altering its color between deep blue and colorless state according to on/off state of incident light.The device consists of a working electrode with planar integration of photovoltaic(PV)and electrochromic(EC)elements on one electrode,a platinum counter electrode and a redox electrolyte comprising Br^-/Br_3^-couple.A high transmittance modulation of 41%at 582 nm is obtained.Electrical energy converted from light is not only sufficient to drive the device,but also can be outputted to the external circuit.