Sensitivity Tunable Inductive Fluid Conductivity Sensor Based on RF Phase Detection

New results are presented for a sensitivity-tunable, inductive fluid conductivity sensor based on RF phase detection. An electronically controlled RF phase shifter allows the sensor to function in a wide range of conductivities from 2-70 mS/cm and helps tune the sensitivity of the response in a selected conductivity range. The noncontact nature of the sensor makes it suitable for corrosive fluids. Furthermore, the small size of the sensing element (1 inch. Sq X 6 mm thick) makes it suitable for compact in-line and hand held monitoring systems.     

Rapid composite bonded repair for helicopter tail drive shafts

Helicopter tail drive shafts (TDS) are safe-life items with strict limits on allowable damage. Typically, shafts with scratches as small as several thousandths of an inch may require replacement. Despite these severe tolerances on damage, TDSs are designed with relatively large ballistic damage tolerance. In battle damage scenarios, repair for damage to TDS caused by small arms fire is required to enable the helicopter to continue its mission or return safely to base. This paper describes a novel repair technique using composite bonded patches to restore the strength of damaged TDSs. Analytical approaches are provided for the design of the repair. An experimental testing program was conducted to validate the theoretical results. It has been demonstrated in this study that the proposed composite bonded repair possessed sufficient static and fatigue strength to restore the structural integrity of the TDS even with minimal surface treatment.     

Nanoscale ferroelectric information storage based on scanning nonlinear dielectric microscopy

An investigation of ultrahigh-density ferroelectric data storage based on scanning nonlinear dielectric microscopy (SNDM) is described. For the purpose of obtaining fundamental knowledge on high-density ferroelectric data storage, several experiments on nanodomain formation in a lithium tantalate (LiTaO3) single crystal were conducted. Through domain engineering, a domain dot array with an areal density of 1.5 Tbit/inch2 was formed on congruent LiTaO3 (CLT). Sub-nanosecond (500 psec) domain switching speed also has been achieved. Next, actual information storage is demonstrated at a density of 1 Tbit/inch2. Finally, it is described that application of a very small dc offset voltage is very effective in accelerating the domain switching speed and in stabilizing the reversed nano-domain dots. Applying this offset application technique, we formed a smallest artificial nano-domain single dot of 5.1 nm in diameter and artificial nano-domain dot-array with a memory density of 10.1 Tbit/inch2 and a bit spacing of 8.0 nm, representing the highest memory density for rewritable data storage reported to date.     

Fabrication of silicon oxide nanodots with an areal density beyond 1 teradots inch(-2)

The combination of solvent annealing, surface reconstruction, and a tone-reversal etching procedure provides an attractive approach to utilize block copolymer (BCP) lithography to fabricate highly ordered and densely packed silicon oxide nano-dots on a surface. The obtained silicon oxide nano-dots feature an areal density of 1.3 teradots inch(-2) .     

A waveshifter light collector for a water Cherenkov detector

A device has been developed which is capable of doubling the light collection capability of a 5 inch hemispherical photomultiplier tube. Known as a “waveshifter plate”, its geometry is adaptable to various applications. Its marginal cost is small with respect to that of a phototube, it is readily removable, and it has minimum effect upon dark noise and timing resolution.     

成批抛光钢球表面缺陷自动检测的图像预处理方法

针对目前企业缺乏钢球表面缺陷检测装备,特别是小直径钢球检测装备的现状,笔者研制开发出一套基于机器视觉、可批量检测小直径钢球表面缺陷的新装备.由特制机电装置将钢球成批自动行列相间地上料并使球面翻滚,相机以一定帧频拍摄多幅钢球表面图像.在保证检测精度和效率的前提下,设计出应用于该装置的图像预处理方法,包括模板标定、图像分割和图像增强.实际检测试验证明,该预处理方法一方面使表面缺陷突显,有利于后期检测,另一方面抑制外接环境引入的各种干扰,消除不必要的影响因素.     

The effect of Fe-doped magnesium oxide thin film in alternative current plasma display panel

In order to improve the discharge characteristics of MgO thin film as a protective layer in an alternative current plasma display panel, Fe-doped MgO thin films was introduced. Both the surface characteristics of the deposited thin films and the electro-optical properties of 4 inch test panels were investigated. It has been demonstrated experimentally that ac PDP with Fe-doped MgO protective layer has lower discharge voltage than that of undoped MgO film, which corresponds to measured secondary electron emission coefficients. The crystallinity and surface roughness of thin films were determined by XRD patterns and AFM images.     

Uniformity control of 3 inch GaN/InGaN layers grown in Planetary Reactors®

We present results obtained from a 2400G3HT reactor with a maximum wafer capacity of 8×3 inch. To achieve uniformity of the growth, we increased the temperature uniformity on each satellite to 0.9°C and that from satellite to satellite to 0.8°C. The optimum reactor geometry has been found by extensive modeling of the reactor design. Thus, an optimization of uniformity and efficiency has been achieved. GaN, InGaN/GaN multi quantum wells, GaN:Si, GaN:Mg and AlGaN were obtained on 5×3 inch substrates by simple scaling of the corresponding process parameters of the 6×2 inch configuration. We demonstrate GaN:Si and GaN:Mg doping uniformity with a standard deviation of less than 5%, with thickness uniformities of less than 1.7% standard deviation without any edge exclusion. InGaN/GaN, quantum well emission at 480 nm shows a standard deviation of 1–2% without rim exclusion. We grew AlGaN with about 10% Al content and less than 2% standard deviation in Al composition across the 3 inch substrate. Simple electroluminescence test structures, consisting of a GaN:Si buffer, followed by a five-period InGaN/GaN quantum well and covered by a GaN:Mg cap with emission wavelengths of about 460 nm show wavelength variations across 3 inch wafers of less than 3 nm. All these results demonstrate that the AIXTRON Planetary Reactor® is a very flexible tool for mass production application, especially with respect to upgrading the system to larger wafer diameters, as is already well known from the standard GaAs and InP applications that are available up to 5×8 inch configurations.     

A high speed magnetic printer

The potential virtues of magnetic printers have long been appreciated [1]. They include quiet, non-impact operation, high speed, the use of plain paper, and minimal sensitivity to humidity conditions. We report on a magnetic printer that has been extensively tested and shown to demonstrate these advantages. The tests have concentrated on the system's performance as a high speed printer of alphanumeric characters selected by a coded digital input. However, the system can also function as a plotter of any figure that can be composed from arrays of dots. The principal features are the following: Any format of alphanumeric characters may be printed at an appropriate line density. The rows of characters may be up to 14 inches long. Paper speed is normally 16.7 inches/sec. Thus, at the common density of 6 lines/inch, the printer operates at 6000 lines/minute. The stationary printing heads can produce a 14 inch long row of dots across the width of the paper. Dot density is 120 dots/inch in this transverse direction. In the longitudinal direction of paper travel, the dot density is generally maintained at 96 dots/inch. The 1672 printing locations on the magnetic recording head are selected by a coincidnt current scheme that utilizes novel integrated drive circuitry. The head "writes" the characters as magnetic latent images composed of dots on a 16 inch wide continuous loop of magnetic tape. The magnetic image is "developed" by exposing the tape to a dry magnetic ink which is attracted to the written dots. The ink images are transferred to paper and sealed by heated rollers.     

High Power Laser for Peening of Metals Enabling Production Technology

Laser shot peening, a surface treatment for metals, is known to induce compressive residual stresses of over 1 mm (0.040 inch) depth providing improved component resistance to various forms of failure. Additionally recent information suggests that thermal relaxation of the laser induced stress is significantly less than that experienced by other forms of surface stressing that involve significantly higher levels of cold work. We have developed a unique solid state laser technology employing Nd:glass slabs and phase conjugation that enables this process to move into high throughput production processing.     

Photostress

The Photos tress photoelastic surface coating technique is a powerful new method o( investigating strain distributions and measuring strain values in prototype components and assemblies. Directions of principal strains can be found to an accuracy of ±2° and magnitudes to approximately ± 10 micro inches per inch. The technique can be used for dynamic and post yield studies in addition to static elastic investigations.     

Experimental study and modelling of heat transfer during condensation of pure fluid and binary mixture on a bundle of horizontal finned tubes

An experimental investigation was conducted to measure the local heat transfer coefficient for each row in a trapezoidal finned horizontal tube bundle during condensation of both pure fluid (HFC 134a) and several compositions of the non-azeotropic binary mixture HFC 23/HFC 134a. The test section is a 13×3 (rows × columns) tube bundle and the heat transfer coefficient is measured using the modified Wilson plot method. The inlet vapour temperature is fixed at 40 °C and the water flow rate in each active row ranges from 170 to 600 l/h. The test series cover five different finned tubes all commercially available, K11 (11 fins/inch), K19 (19 fins/inch), K26 (26 fins/inch), K32 (32 fins/inch), K40 (40 fins/inch) and their performances were compared. The experimental results were checked against available models predicting the heat transfer coefficient during condensation of pure fluids on banks of finned tubes. Modelling of heat exchange during condensation of binary mixtures on bundles of finned tubes based on the curve condensation model is presented.     

Protein detection based on small molecule-linked DNA

Based on small molecule-linked DNA and the nicking endonuclease-assisted amplification (NEA) strategy, a novel electrochemical method for protein detection is proposed in this work. Specifically, the small molecule-linked DNA (probe 1) can be protected from exonuclease-catalyzed digestion upon binding to the protein target of the small molecule, so the DNA strand may hybridize with another DNA strand (probe 2) that is previously immobilized onto an electrode surface. Consequently, the NEA process is triggered, resulting in continuous removal of the DNA strands from the electrode surface, and the blocking effect against the electrochemical species [Fe(CN)(6)](3-/4-) becomes increasingly lower; thus, increased electrochemical waves can be achieved. Because the whole process is activated by the target protein, an electrochemical method for protein quantification is developed. Taking folate receptor (FR) as an example in this work, we can determine the protein in a linear range from 0.3 to 15 ng/mL with a detection limit of 0.19 ng/mL. Furthermore, because the method can be used for the assay of FR in serum samples and for the detection of other proteins such as streptavidin by simply changing the small molecule moiety of the DNA probes, this novel method is expected to have great potential applications in the future.     

SERS biodetection using gold-silica nanoshells and nitrocellulose membranes

We have developed a rapid, reproducible, easy to execute, surface enhanced Raman scattering (SERS) method for detection of low volumes and total amounts of biological antigens using an analyte capture system derived from methods commonly used in Western blotting. Our method is a "half-sandwich" assay with an antigen detection scheme that employs a nitrocellulose (NC) membrane with 200 nm pore size to capture subnanograms of analyte and concentrate them in a small area from applied volumes as low as one microliter. The SERS probes used for detection consist of gold-silica nanoshells modified with a two-component mixed monolayer system. One component consists of a poly(ethylene glycol) (PEG)-modified Raman-active chromophore bound to the gold surface which allows for SERS detection and imparts particle stability. The second component uses (ortho-pyridyl) disulfide-PEG-succinimidyl ester to couple the recognition antibody to the particle surface. By controlling the reaction time and concentration of thiols, a mixed monolayer is prepared on the nanoshell surface with the ability to recognize low concentrations of analyte and generate reproducible SERS signals. Using this strategy, we have achieved SERS signals that are proportional to antigen present on the membrane allowing detection of total antigen amounts as low as 1.25 ng for some cases. The performance of this new SERS bioassay has been tested with a variety of potential antigens, demonstrating the potential for multiplexed detection of analytes.     

PZT薄膜的MOCVD制备技术

采用直接液体榆运-金属有机化合物化学气相沉积技术（DLI-MOCVD）制备Pb（ZrxTi1-x）O3薄膜（PZT薄膜）,并进行了相关研究,通过调节MOCVD中影响PZT质量的主要工艺参数（温度、压力、系统的气体（Ar,O2）流量、衬底转速、蠕动泵速）,制备不同组分PZT薄膜（均匀性≥±95％,尺寸为2．54—20．32cm（1—8in）,厚度为50—500nm）．经XRD测试可见,PZT薄膜已形成钙钛矿结构．用SEM对其表面进行分析,结果表明,PZT薄膜表面致密均匀．     

Detection of cortisol in saliva with a flow-filtered, portable surface plasmon resonance biosensor system

Saliva provides a useful and noninvasive alternative to blood for many biomedical diagnostic assays. The level of the hormone cortisol in blood and saliva is related to the level of stress. We present here the development of a portable surface plasmon resonance (SPR) biosensor system for detection of cortisol in saliva. Cortisol-specific monoclonal antibodies were used to develop a competition assay with a six-channel portable SPR biosensor designed in our laboratory. The detection limit of cortisol in laboratory buffers was 0.36 ng/mL (1.0 nM). An in-line filter based on diffusion through a hollow fiber hydrophilic membrane served to separate small molecules from the complex macromolecular matrix of saliva prior to introduction to the sensor surface. The filtering flow cell provided in-line separation of small molecules from salivary mucins and other large molecules with only a 29% reduction of signal compared with direct flow of the same concentration of analyte over the sensor surface. A standard curve for detection of cortisol in saliva was generated with a detection limit of 1.0 ng/mL (3.6 nM), sufficiently sensitive for clinical use. The system will also be useful for a wide range of applications where small molecular weight analytes are found in complex matrixes.     

Demagnetization-free longitudinal recording on flexible thin film metal media

The variation of demagnetization effects with media parameters for longitudinal contact recording has been investigated. Co-Re thin film metal media were sputtered onto flexible polyimide substrates. It was found that when the film thickness δ and demagnetizaton parameterB_{r}delta/H_{c}were less than 2 μ inch and 15 μinch, respectively, demagnetization-free longitudinal recording was obtained up to the recording density of 75 KFRPI at the head-to-medium spacing of 3 μ inch. As a result, recording densities of D50over 50 KFRPI were achieved with a 20 μinch gap head. For thicker films with larger demagnetization parameters, i.e.,delta geq 4 muinch andB_{r}delta/H_{c} geq 40 muinch, the longitudinal recording process approached the demagnetization limit. The results show that (with existing head field gradients) improvement in linear density of thin metal media can be obtained by an approximate factor of two before the demagnetization limit is reached.     

Label-free plasmonic detection of biomolecular binding by a single gold nanorod

We report the use of individual gold nanorods as plasmonic transducers to detect the binding of streptavidin to individual biotin-conjugated nanorods in real time on a surface. Label-free detection at the single-nanorod level was performed by tracking the wavelength shift of the nanorod-localized surface plasmon resonant scattering spectrum using a dark-field microspectroscopy system. The lowest streptavidin concentration that was experimentally measured was 1 nM, which is a factor of 1000-fold lower than the previously reported detection limit for streptavidin binding by biotinylated single plasmonic nanostructures. We believe that the current optical setup is able to reliably measure wavelength shifts as small as 0.3 nm. Binding of streptavidin at 1 nM concentration induces a mean resonant wavelength shift of 0.59 nm suggesting that we are currently operating at close to the limit of detection of the system.     

基于改进YOLOv4算法的轮毂表面缺陷检测

汽车轮毂加工过程中产生的表面缺陷严重影响整车的美观性及服役性能,针对人工检测效率低、漏检率高的问题,提出一种基于改进YOLOv4算法的轮毂表面缺陷检测方法。构建了轮毂缺陷数据集,其包含6种表面缺陷,由2346张4928×3264pixel的图像组成;采用K-means方法进行先验框聚类,并针对YOLOv4算法在纤维、粘铝等小尺度缺陷上检测精度不足问题,在原网络Neck部分引入细化U型网络模块(TUM)和注意力机制,用于增强有效特征并抑制无效特征,强化多尺度特征提取与融合,改善特征处理过程中可能存在的小目标信息丢失问题;基于该数据集,训练并测试不同算法的缺陷检测性能并验证改进模块的有效性。结果表明,该方法大幅提升了粘铝等小尺寸缺陷的检测能力,缺陷检测平均精度达到85.8%,与多种算法相比较检测精度最高。