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This paper presents an automatic and online FDD (fault detection and diagnose) and sensor reconstruction scheme that can be used in a building energy management and control system to detect and diagnose sensor faults and reconstruct faulty sensors in building central chilling systems. The scheme is based on principal component analysis to build a model that captures the correlation among the flow meters and temperature sensors installed in the chilling systems. The model is employed to reconstruct an assumed faulty sensor. The square prediction error based on the model and the sensor validity index based on the construction are employed, respectively, to detect the sensor fault and identify the faulty sensor. An existing building central chilling system is simulated to test and validate the developed scheme online. Four types of sensor faults are introduced, respectively, during the simulation to validate the sensor FDD and sensor reconstruction scheme.

A new experimental procedure was proposed based on genetic algorithm for analyzing exterior wall surface heat transfer process and deducing exterior wall surface heat transfer coefficient under actual conditions. Tests were carried out under a wide range of conditions, and the heat transfer coefficient was found vary from 14.315 to 24.412 W/m2 K while wind speed ranged from 1.04 to 7.36 m/s, and correlation was obtained in terms of the wind speed. Tests revealed that the commonly used correlation for predicting the heat transfer coefficient was overestimated, especially at high wind speeds.

This paper presents the transmission matrix and frequency characteristics of transient heat conduction through a multilayer cylindrical structure. The frequency-domain regression method [Appl. Thermal Eng. 21 (6) (2000) 683] is introduced to estimate some simple polynomial s-transfer functions from the frequency characteristics and further calculate the transient heat flow of the cylindrical structure including its thermal response factors and Z-conduction transfer function coefficients. The calculation examples and comparisons have fully demonstrated that the developed procedure is not only easy and simple, but also has high computation accuracy and efficiency.

The transmission matrix and frequency characteristics of transient heat conduction through a multilayer spherical structure are presented by applying Laplace transforms in this paper. The frequency domain regression (FDR) [S.W. Wang, Y.M. Chen, Appl. Thermal Engrg. 21 (6) (2000) 683] method is introduced to construct some simple polynomial s-transfer functions from the frequency characteristics. The polynomial s-transfer functions are further used to calculate the transient heat flow of the spherical structure including its thermal response factors and Z-conduction transfer function (CTF) coefficients. This approach is very easy and simple to implement in programming and avoids the case of missing roots in finding the roots of characteristic equation. The examples and comparisons have demonstrated that this approach has high computation accuracy.

A frequency-domain regression method is developed for transient heat flow calculation of multilayer constructions, which estimates a simple polynomial s-transfer function of transient heat conduction in a building construction on the basis of its theoretical frequency characteristics. This simple polynomial s-transfer function is completely equivalent to the hyperbolic s-transfer function in terms of frequency characteristics. First, the frequency characteristics of the total transmission matrix are calculated within the frequency range concerned. Then, a set of linear equations is solved to yield a simple polynomial s-transfer function for internal, cross and external heat conduction, respectively. Finally, the response factors or CTFs are obtained simply by applying inverse Laplace transforms or Z-transforms on the polynomial s-transfer function. The validations and comparisons show that this method has high accuracy and efficiency and has no stability problem.

Comfort index-based control has become the tendency of the development of new HVAC control systems, while an effective sensor for thermal comfort index is indispensable to a successful comfort index-based HVAC control system. Based on detailed discussions on calculating and measuring the equivalent temperature, predicted mean vote (PMV) and standard effective temperature (SET*), a comfort sensor with a new structure is proposed in this paper. The proposed PMV and SET* measurement instrument consists of an equivalent temperature sensor, a relative humidity sensor and a temperature sensor. By utilizing this sensor we can “measure” the PMV and SET* of an imaginary environment, which is extended from that defined in the concept of the equivalent temperature by Madsen (ASHRAE Transactions 1984;90(1):1077–90). Furthermore, we show that the PMV and SET* of the imaginary environment are almost the same as the actual ones. Simulation results have verified that the suggested PMV and SET* sensor can have a good measurement of PMV, while for SET* more research work is needed to improve the accuracy of its measurement. Most importantly, more practical work, including calibration validation and test of its sensitivity to the variation of environment variables in real conditions, need to be performed.

This paper describes a supervisory control scheme that adapts to the presence of the measurement faults in outdoor air flow rate control using sensor-based demand-controlled ventilation, maintains an adequate indoor air quality and minimizes the resulting increase in energy consumption. A strategy, which is based on neural network models, is employed to diagnose the measurement faults of outdoor and supply flow sensor, and accomplishes the fault-tolerant control of outdoor air flow when faults occur. The neural network models are trained using the data collected under various normal conditions. The residuals between the measurements of flow sensors and the outputs of the neural network models are used to diagnose the faults. When the fault of outdoor or supply air flow sensor occurs, the recovered estimate of outdoor or supply air flow rate obtained on the basis of the neural network models is used in the feedback control loop to regain the control of outdoor air flow. Tests using dynamic system simulation are conducted to validate the strategy. The control, IAQ and energy performances of the system under fault-tolerant control strategy in the presence of the faults in air flow sensor are also presented.

This paper presents a simple procedure for calculating the thermal response factors and conduction transfer functions (CTFs) of a multilayer wall on the basis of the polynomial s –transfer functions, which are estimated by frequency-domain regression (FDR) method from the theoretical frequency characteristics of transient heat conduction through the wall. Computation examples demonstrate that the FDR method is accurate, simple and efficient in calculating the thermal response factors and CTFs of walls.

A new experimental procedure is proposed based on an instrumental variable method [1] for analyzing wall surface heat transfer processes and deducing wall surface heat transfer coefficients under actual conditions. Tests were carried out under a wide range of conditions, and the heat transfer coefficient was found to vary from 8 to 26 W/m 2 ” K while wind speed ranged from 0 to 7.5 m/s, and correlations were obtained in terms of wind speed. In addition, the experiments indicated that wind direction does not have a significant effect on the heat transfer coefficient of wall surfaces.

The long-term contamination and carbonization of Si(1 1 1) surfaces in ultrahigh vacuum (UHV) was investigated by high-resolution electron-energy loss spectroscopy (HREELS), Auger electron spectroscopy (AES), and scanning tunneling microscopy (STM). HREELS measurements show that O-2, carbon-containing molecules, H, and OH-containing molecules of the residual gases in UHV gradually absorb on Si surfaces. After 6 days' absorption of residual gases, AES measurements indicate that the coverage of carbon and oxygen on a Si surface increased up to 18 and 12%, respectively. When the surface is covered by residual gases in UHV and then flashed to 1250 degreesC for a few times, islands of SiC are epitaxially grown on the Si(1 1 1)-(7 x 7) surface. Highly oriented SiC islands in the shape of equilateral triangles are observed by STM. The carbonized Si surface in UHV is flat on the atomic scale throughout the whole surface. Carbonization of a Si surface in UHV may be an effective way to form a perfect interface between epitaxial SiC thin films and the Si(I 1 1) substrates. (C) 2001 Elsevier Science B.V. All rights reserved.

The conduction transfer function (CTF) models of heat conduction through building constructions are widely used in building energy analysis and heating, ventilation, and air conditioning (HVAC) system design and simulation. A frequency-domain regression (FDR) method is developed to estimate the CTF model of a building construction from its theoretical response characteristics in this paper. First, the theoretical response characteristics are calculated simply by numerical matrix multiplication. The CTF coefficients are then obtained by simply solving a set of linear equations. The tests and comparisons have shown that CTF models obtained by the FDR method are completely equivalent to those found by the methods currently available. The FDR method can provide a short series of CTF coefficients, and the models by this method have a high accuracy in calculating heat gain/loss through building constructions. The FDR method is very simple and straightforward, has high computational speeds, and needs less computational efforts. Therefore, the FDR method is much easier and convenient to use and implement in building energy analysis and HVAC system simulation programs.

Moisture transfer in building components and furnishings has significant effect on indoor air humidity and latent cooling load. Many mathematical models and calculation methods have been proposed to evaluate this effect. Simple but accurate models are what the users expect. Investigation shows that the one-dimensional linear moisture transfer model, which uses the vapor pressure as the unique driving potential, is both very simple and well match the real moisture transfer characteristics of most air-conditioned buildings. Frequency analysis shows completely consistent characteristics between the transfer function model of moisture sorption by interior surface materials and the one-dimensional linear moisture transfer model through the entire wall within the frequency range that should be concerned. It also shows that the moisture penetration across the wall is neglectable. The transfer function model of moisture sorption by interior surface materials is not only very simple but also has satisfactory accuracy to evaluate the moisture transfer effect of buildings on indoor air humidity and latent cooling load.

Based on polynomial s-transfer functions of transient heat conduction through a building construction, a novel and simple model is developed for building thermal load calculation. The polynomial s-transfer functions are estimated from the theoretical frequency responses of the building construction by frequency-domain regression method. The simple polynomial s-transfer functions are completely equivalent to the hyperbolic s-transfer functions in terms of frequency characteristics. First, the frequency responses of the total transmission matrix are calculated within the frequency range concerned. Then, a set of linear equations is solved yielding a simple polynomial s-transfer function for cross and internal heat conduction. Finally, simple recursive formulae are obtained by inverse Laplace transforms and discretization of the convolution integrals. The coefficients of the model are independent from time step and the time step can be varied according to the requirement during simulation. Validations and comparisons show that this model has fast computation speed and no numerical unstability, and provides high accuracy and good flexibility to the requirement of variable time step.

The z -transfer function technique is used in calculation for HVAC design and building energy consumption. Theoretical calculation methods to determine the z -transfer function coefficients, which characterize the dynamic thermal performance of building components, do exist, but these depend on a number of assumptions and one must supplement them with experimental techniques. This paper discusses a neural-network-based system identification technique to determine the z -transfer function of a building envelope from experimental data. A multi-layer neural network is trained by the samples constructed from the dynamically measured data of heat conduction process through a wall. The Markov parameters, which are produced from the weighting matrices of the network, are utilized to realize the minimal state space model of the wall by eigensystem realization algorithm. The z -transfer function coefficients are obtained by the algorithm transforming the state space model into z -transfer function. The results show that this technique has some advantages in programming and computational simplicity, very good properties of noise rejection and improved accuracy of the results. The training time of the network is greatly reduced by adopting the adaptive learning algorithm.

This paper discusses the difference between other uncertain theories such as stochastic and gray system one and the uncertainty of building heat-moisture system. The other prediction techniques are simply analyzed, and gray prediction theory is stated. A method based on gray prediction model is proposed. Building energy consumption for a certain example is predicted. By inspecting, predicting values agree with measured one very much, that is, the GM(1,1) model compares with the original load data. The method can be seen as a new load calculation method and applied for verification purposes.

A transfer function approach has been described to calculate dynamic moisture absorption and desorption by building materials in the hygroscopic range, and the dynamic moisture absorption and desorption processes have been theoretically modeled. Their surface vapor pressure and moisture absorption and desorption flux can be evaluated by this approach. It has turned out mathematically that the material surface attains instantaneous moisture equilibrium with the surroundings at high Biot number (Bi → ∞), and that the material moisture behavior can be described through a lumped-parameter modeling at low Biot number (Bi → 0). For building materials at intermediate Biot number, comparisons with experimental results and numerical solutions have shown satisfactory agreement with the proposed approach. Using this approach, the dynamic response of moisture absorption and desorption in interior building materials to the variation of indoor air humidity and the dynamic effect of moisture absorption and desorption by building interior materials on indoor air humidity and space latent cooling load can be simultaneously calculated.

To explore the relationship between metabolic syndrome (MS) and risk for chronic kidney disease (CKD) in a Southern Chinese population.A cross-sectional study was conducted in 1724 community-based Southern Chinese participants from June to October 2012. The prevalence of MS (as defined by the International Diabetes Federation) and CKD (defined as an estimated glomerular filtration rate of60 mL/min per 1.73 m(2) and/or albuminuria) was determined. The association between MS and CKD was then analyzed using STATA software.Metabolic syndrome was significantly associated with CKD (P0.001) in the unadjusted analyses as well as after adjustment for potential confounders. The unadjusted odds ratio and adjusted odds ratio for MS were 3.53 (95% confidence interval (CI) 2.62 to 4.75, P0.001) and 2.52 (95% CI 1.84 to 3.54, P0.001). When further adjusted for diabetes and hypertension, the association of MS and CKD was significant (odds ratio (OR) 1.63, 95% CI 1.15 to 2.32, P = 0.006). After adjustment for potential confounders, three components and four/five components were associated with CKD. The OR for three components and four/five components were 2.90 (95% CI 1.70 to 4.96, P0.001) and 3.64(95% CI 1.95 to 6.80, P0.001), when compared with those without components. High blood pressure, high serum triglyceride level, elevated fasting glucose level and central obesity were associated with CKD (P0.05). The odds ratios for elevated blood pressure, elevated serum triglyceride levels, elevated fasting glucose and central obesity were 1.80 (95% CI 1.25 to 2.62, P = 0.002), 1.56 (95% CI 1.14 to 2.14, P = 0.006), 2.54 (95% CI 1.82 to 3.57, P0.001), and 1.50 (95% CI 1.10 to 2.07, P = 0.01), respectively.These findings suggest that MS is associated with CKD in Southern Chinese population, which may provide important information for the overall control of these diseases.

Double-skin facade systems (DSF), as one of the newest kind of envelops of buildings, is attracting more and more architects and investors’ attention in China. The skins can be air tight or ventilated. As for the ventilated DSF, airflow passing through the cavity can be naturally driven, mechanically driven, or a combination of both. According to some previous studies, buildings constructed with DSF may have better energy performance than the conventional single-skin facade. The problem is that, presently, there are still no official specifications which can help the engineers to thoroughly understand the complex thermal and airflow behavior of DSF. This paper presents a detailed simulation process for an office building equipped with naturally ventilated DSF under the climatic condition in Changsha. A theoretical model is developed via the EnergyPlus simulation program to evaluate the thermal performance of double-skin facade with different configurations. The results obtained in this paper can be valuable for engineers to do some optimization work during the design process under the hot summer and cold winter climates. It indicates that a reasonably constructed DSF can provide an annual saving of around 30 % in building cooling energy, and up to 10 % as for the heating energy, compared to a conventional single-skin facade.

In order to optimize building energy consumption, it is essential to reduce the heat losses and gains through the building envelope by selecting proper materials which are often porous. However, heat transfer and moisture transfer are often highly coupled, so coupled heat and moisture transfer in two common walls (aerated concrete wall and red brick wall) were studied in this paper. Aerated concrete wall is made up by aerated concrete block, cement mortar, and lime–cement mortar. It is widely used now for the superior thermal insulation of aerated concrete block. Red brick wall is made up by aerated concrete block, cement mortar, and lime–cement mortar. It was frequently used in China decades ago, and many existing building are made up by red brick wall. After a simple review of the development of models for coupled heat and moisture transfer in porous media, a dynamic model was proposed which takes into account most of the main hydrothermal effects. It takes temperature and air humidity ratio of the porous media as the critical driving potentials. Then the model was used to simulate coupled heat and moisture transfer in both aerated concrete wall and red brick wall and then analyzed comparatively. Results show that aerated concrete wall can reduce more heat transfer than red brick wall. However, aerated concrete wall may accumulate moisture and cause moisture damage more easily.

Objective To the best of our knowledge, the association of insulin resistance (IR) with chronic kidney disease (CKD) has not been well studied in normal-weight individuals. The aim of this study is to examine whether IR is associated with CKD in non-diabetic subjects with normal weight. We also examine whether the presence of obesity modifies the association of IR with CKD. Methods Data were drawn from a cross-sectional survey in China. Both estimated glomerular filtration rate and urinary albumin to creatinine ratio were used as markers of CKD. Logistic regression models and the quartiles of homeostatic model assessment of insulin resistance were used to explore the associations of IR with CKD in entire cohort, normal-weight and overweight/obese subpopulations. Results In normal-weight subpopulation, the prevalence of IR and metabolic syndrome were 11.11% and 8.99%, respectively. In the entire cohort, the highest quartile HOMA-insulin resistance had a 70% increased risk for CKD (RR 1.70, 95% CI 1.07, 2.71, P=0.03, comparing the highest to the lowest quartile). However, when adding obesity to the model, the association was abolished. IR was associated with CKD in overweight/obese subpopulation but not in normal-weight subpopulation. Conclusion IR and MetS in normal-weight individuals is common in the Chinese population. IR is associated with CKD in overweight/obese subpopulation but not in normal-weight subpopulation and the presence of obesity modifies the association of IR with CKD.

The purpose of the study was to explore the association between metabolic syndrome (MetS) and chronic kidney disease (CKD) in perimenopausal women. A cross-sectional study was conducted in Zhuhai from June to October 2012. Perimenopausal women (n = 685) were included in the study. All participants were divided into three subgroups: Group 1, 40 years old ≤ Age &lt, 50 years old, Group 2, 50 years old ≤ Age &lt, 60 years old, Group 3, 60 years old ≤ Age ≤ 65 years old. MetS was associated with CKD (p &lt, 0.01) in the unadjusted analyses in total subjects. After adjusting the potential confounders, the odd ratios of CKD for MetS was 2.66 (95% CI 1.56 to 4.49, p &lt, 0.001). There was no relationship between MetS and CKD in both Group 1 and Group 3. MetS was associated with CKD (p &lt, 0.001) in the unadjusted analyses in Group 2. After adjusting for potential confounders, MetS was significantly associated with CKD. The odd ratios for MetS was 6.79 (95% CI 2.30 to 20.09, p &lt, 0.001). There was no relationship between elevated blood pressure, elevated fasting glucose, abdominal obesity, Low HDL cholesterol, elevated triglycerides and CKD in both Group 1 and Group 3. Elevated blood pressure was associated with CKD in Group 2 (unadjusted Odds ratio: 4.52 (1.28–16.02), p = 0.02). After adjusting for potential confounders, there was no relationship between elevated blood pressure and CKD (p = 0.78). Elevated fasting glucose was associated with CKD in Group 2 (unadjusted Odds ratio: 3.69 (1.10–12.38), p = 0.03). After adjusting for potential confounders, there was no relationship between elevated fasting glucose and CKD (p = 0.15). There was no relationship between abdominal obesity, Low HDL cholesterol, elevated triglycerides and CKD in Group 2. These findings suggest that in perimenopausal women aged from 50 or older to 60 MetS was associated with CKD. There is no relationship between MetS and CKD in perimenopausal women aged from 40 or older to 50 and aged from 60 or older to 65.

We present a special high spectral resolution lidar (HSRL) by using a novel tunable fiber based transmitter. The transmitter can produce 50μJ pulse energy at 1064nm and >25μJ pulse energy at 532nm with 10 kHz repetition rate, 5ns pulse width, respectively. A key advantage of the transmitter is the frequency-tunability. The laser can be tuned over the Iodine absorption lines from 1111 to 1104. The laser has a ~130MHz linewidth at 1064nm close to the transform limit linewidth ~ 88MHz for a pulse width of 5ns. Even though it was not frequency locked, the laser has very good frequency stability, which is on the order of ~200MHz over minutes. The beam quality M 2 is less than 1.5. All the preliminary transmitter parameters meet the basic requirements of a HSRL. The transmitter was implemented in UMBC’s lidar lab that includes a ceiling hatch to enable vertical propagation and viewing of transmitted laser beams into the atmosphere. The atmospheric measurement demonstrates good agreement of the signal to the model Rayleigh decay over the profile range with no significant deviations. Most importantly, these results show that the measurement successfully suppresses the Mie scattering from clouds while recovering the full molecular signal as expected.

BACKGROUND: High serum levels of lipopolysaccharide (LPS) with LPS-MD-2/TLR4 complex activated NF-kb and cytokine cause hepatic necrosis in animal models. We investigated the dynamic changes of LPS levels in patients with acute on chronic hepatitis B liver failure (ACHBLF). METHODS: We enrolled ACHBLF patients for a 12-week study. Patients' LPS levels were measured along with 10 healthy controls. Patients on supportive care and recovered without intervention(s) were analyzed. Patients' LPS levels during the disease progression phase, peak phase, and remission phase were compared with healthy controls. RESULTS: Among 30 patients enrolled, 25 who received interventions or expired during the study period were excluded from the analysis, five patients on supportive care who completed the study were analyzed. Significant abnormal distributions of LPS levels were observed in patients in different phases (0.0168±0.0101 in progression phase; 0.0960±0.0680 in peak phase; 0.0249±0.0365 in remission phase; and 0.0201±0.0146 in controls; respectively, p

5W peak power at 911 nm is demonstrated with a pulsed Neodymium (Nd) doped fiber master oscillator power amplifier (MOPA). This result is the first reported high gain (16dB) fiber amplifier operation at 911nm. Pulse repetition frequency (PRF) and duty-cycle dependence of the all fiber system is characterized. Negligible performance degreadation is observed down to 1% duty cycle and 10 kHz PRF, where 2.5μJ of pulse energy is achieved. Continuous wave (CW) MOPA experiments achieved 55mW average power and 9dB gain with 15% optical to optical (o-o) efficiency. Excellent agreement is established between dynammic fiber MOPA simulation tool and experimental results in predicting output amplified spontaneous emission (ase) and signal pulse shapes. Using the simulation tool robust Stimulated Brillion Scattering (SBS) free operation is predicted out of a two stage all fiber system that generates over 10W's of peak power with 500 MHz line-width. An all fiber 911 nm pulsed laser source with >10W of peak power is expected to increase reliability and reduce complexity of high energy 455 nm laser system based on optical parametric amplification for udnerwater applications. The views expressed are thos of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government.

Novel tapered Yb-doped polarization-maintaining (PM) large-mode-area (LMA) fibers were fabricated, with 25/250μm and 40/400μm core/clad at each end, and used in the last stage of a multi-stage Yb-fiber MOPA. The fiber-MOPA is controlled by high-speed FPGA for real-time control of the seed laser diode modulation, electro-optic modulator and acousto-optic modulator. Stable 0.3nsec pulses at 10kHz rate with 0.3mJ pulse energy (1MW peak power) is demonstrated. At 1nsec pulsewidth, scaling to >0.5mJ pulse energy is demonstrated. Polarization extinction ratio of 17dB is obtained with diffraction limited beam quality and excellent (

Research on fault detection and diagnosis of variable air volume (VAV) air-conditioning systems is of great significance for energy conservation and stable operation of the air-conditioning systems. A fault detection and diagnosis (FDD) strategy using a hybrid method is presented for VAV air handling units in this paper. The Cumulative sum (CUSUM) control charts are used to detect faults in air handling units. The CUSUM control charts are used to monitor the temperature errors between the supply air temperature and its setpoint. Faults are detected when the CUSUM values exceed the chart limits. The fault detection method is robust enough to cope with the non-stationary characteristics of the VAV air handling units. Three rule-based fault classifiers consisting of expert rules and fault isolation algorithms are developed to isolate fault sources. The FDD strategy was tested and validated using in real time data from real VAV air-conditioning systems.

We demonstrate a multi-channel architecture for nsec pulsed lidar transmitter, scalable to larger channel counts via wavelength- and time-multiplexing in a multi-stage Yb-fiber amplifier. This technology enables lidar systems for topographic mapping missions, requiring much greater spatial coverage and range resolution. We demonstrate prototype hardware, where wavelength channels at 1060nm, 1061nm and 1064nm are multiplexed, and precise 1.3nsec pulse using LiNbO3 electro-optic(EO) modulators, at a combined repetition rate of 1MHz, with equal time interleaving between the wavelengths. The multiplexed pulses are amplified to >20W average power, in an optimized three-stage Yb-fiber amplifier system. We show simple de-multiplexing and frequency-doubling of one of the wavelengths (1064nm). Highspeed FPGA based control provides for independent and programmable control of the pulse rate, timing trigger, pulsewidth, and the intra-pulse-pattern for improved detection schemes.

KW level fiber based MOPA laser system at 1064nm for uplink deep space communication is developed and characterized. System achieves 11.5 kW peak power (600W average power) at 500 kHz (5% duty cycle) with >70% optical conversion efficiency. Experiments using 16-ary PPM format are presented where without pre-pulse shaping >±60% pulse energy variation is observed. Gain dynamics is identified as main source of pulse to pulse energy fluctuation. Novel, FPGA implementable open loop pulse shaping algorithm is developed and demonstrated. Resulting pulse energy statistics are reported, where

We present results on the design, development and initial testing of a fiber-optic based RF-modulated lidar transmitter operating at 532nm, for underwater imaging application in littoral waters. The design implementation is based on using state-of-the-art high-speed FPGAs, thereby producing optical waveforms with arbitrary digital-RF-modulated pulse patterns with carrier frequencies ≥ 3GHz, with a repetition rate of 0.5-1MHz, and with average powers ≥5W (at 532nm). Use of RF-modulated bursts above 500MHz, instead of single optical pulse lidar detection, reduces the effect of volumetric backscatter for underwater imaging application, leading to an improved signal-to-noise-ratio (SNR) and contrast, for a given range. Initial underwater target detection tests conducted at Patuxent River Naval Air Station, MD, in a large water-tank facility, validates the advantages of this hybrid-lidar-radar (HLR) approach for improved underwater imaging, over a wide range of turbidity levels and both white and black targets. The compact, robust and power-efficient fiber laser architecture lends very well to lidar sensor integration on unmanned-underwater-vehicle (UUV) platforms. HLR transmitters can also provide similar advantages in active-sensing situations dominated by continuous backscatter, e.g. underwater communications, imaging through smoke and fire environment, rotor-craft landing in degraded visual environment, and pointing-tracking of active-EO sensors through fog.

To research the regenerated silk fibroin film (SF) as a biomedical material, we investigate the effects of its modified by the fibroblasts infected by adenovirus mediated-Ang-1 (Ad-Ang-1) on inducing angiogenesis. The WI-38 fibroblasts cultured on the SF and no any film were infected with Ad-Ang-1, they were also infected with adenovirus-green fluorescent protein (Ad-GFP) and treated by phosphate buffered saline (PBS). We observed the cell growth morphology and detected the expression of aim gene Ang-1. The effect of Ad-Ang-1 on the angiogenesis of the chick chorioallantoic membrane was assessed by chorioallantoic membrane (CAM) assay and that inducing corneal neovascularization through the SF modified by transgenic cells implanted into the corneal stroma of rabbits. The expression levels of vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF2), and platelet-derived growth factor (PDGF) were detected by enzyme-labeled immunosorbent assay (ELISA).We demonstrated that adenovirus vector can be efficiently infected into fibroblasts cultured on the SF; the expression levels of Ang-1 in WI-38 cells infected by Ad- Ang-1 cultured on the SF enhanced(P

This work describes the composition and bonding structure of boron carbon nitride (BCxNy) films synthesized by medium frequency magnetron sputtering from a boron target in a N2+CH4+Ar gas mixture. Varying the flow rate of methane in the applied gas mixture was used. The three elements of B, C and N were bonded each other and an atomic-level hybridized B-C-N had been formed in the films. The chemical bonds with carbon (B-C and C=N) were enhanced as carbon content in the films increased. The tribological behavior of BCN thin films was investigated using ball-on-disc tests and 100Cr6 balls as counter-faces. The coefficient of friction was reduced approximately from 0.8 to 0.18, and wear resistance was considerably improved by increasing the ratio of CH4 gas component from 0 to 40 sccm. By adding amount of CH4 (∼ 40sccm) in the deposition process the boron carbon nitride coating exhibited the lowest friction and highest wear resistance.

Nanolamellate structures of CaTiO3 were fabricated by using an in situ hydrothermal synthesis method on titanium for the first time. The number of nanolamellas and the morphology completely or mainly depend on the reaction time and NaOH concentrations, and the wettability of the resulting CaTiO3 surfaces can be successively turned from superhydrophilic to superhydrophobic after modification with a thin layer of hydrophobic silicone, mainly depending on the surface morphology. The proposed formation mechanism of the nanolamellate CaTiO3 structures has also been discussed.

We report on a novel fiber based coherent detection system employing an optical preamplifier, a spectrum bandpass filter, and a time-domain filter. The time-domain filter, a synchronous time gate, reduces the in-band Amplified Spontaneous Emission (ASE ) beat noise, which cannot be achieved by the spectrum bandpass filter alone. In preliminary experiments with a 100 GHz bandpass filter, no degradation is observed from the optically preamplified coherent detection compared to pure coherent detection. With a 10 ns pulse width, 500 kHz repetition rate, and 10 pW input power, 2.78 dB and 1 dB signal-to-noise (SNR) improvement has been achieved, respectively, when 5% and 50% time gating duty cycle is used.

We present a novel electro-optic Q-switching technique that is controlled by an ultrafast optoelectronic feedback loop.

Various military lidar applications such as underwater mine detection, obstacle avoidance, IRCM, and 3 D lidar incorporate high repetition rate solid-state lasers to accomplish the mission. The recent advances and demonstrations in high power Ytterbium (Yb) fiber lasers/amplifiers make the fiber media a viable alternative to bulk lasers for these applications. The fiber laser geometry maximizes the pump absorption and mode matching for overall high efficiency, (factor-of-two over bulk laser sources) while minimizing thermal effects. In this presentation we will show experimental and modeling results on various master oscillator Yb doped polarization maintaining (PM) fiber amplifiers being developed for high repetition rate applications. We have demonstrated >20 W of average output power with M 2

We can accurately predict the performance of YDFAs between the CW regime and 1 MHz operation for pulse widths varying between 1ns and several microseconds. Comparisons between experiments and modeling will be presented.

High spectral purity, high energy, tunable laser sources operating in the absorption bands at 730, 815 or 940 nm bandsare required for remote sensing ofwater vapor mixing ratio with a differential absorption lidar. For this application,injection seeding of a high energy Cr:LiSrAlF6 ring laser with a narrowband, Q-switched, Cr:LiSAF laser wasinvestigated. The slave ring laser utilized either a flashlamp pumped or diode-pumped Cr:LiSAF gain module. Theflashlamp pumped module provided a single-pass gain of 1.5 at 825nm. The diode-pumped module consisted of aCr:LiSAF rod, side-pumped with high power diode bar stacks giving >l5OmJ energy in 2OOs pulse. The spectralbandwidth ofthe ring laser output was 8 to lOnm without injection seeding. The seed Cr:LiSAF laser was end pumpedby a fiber coupled diode laser, and tuned with a birefringent filter. Tuning from 810 to 980nm was possible with twosets of mirrors, and 160 to 700ns long Q-switched pulses, with up to 4OJ energy, at 1000Hz, were obtained withlinewidths of

On the basis of the GaAs photoconductor characteristic of the decrease resistance with the increase of irradiation, we first developed a high precision and ultrafast positive and negative feedback circuit. By using these techniques, we have made a novel method of mode-locking, automatic mode-selecting, Q-switching, and realizing synchronizing outputs of two independent pulse oscillators, the jitter is no more than +/- 1 ns.

In this paper, we use two-photon absorption (TPA) of GaAs, realize the temporal shaping of single longitudinal mode Q-switched pulses. The experimental results agree with the numerical solutions well.

The amorphous chromium (a-Cr) coatings with thickness of 50 μm were electrodeposited from Cr(III) instead of Cr(VI) bath. The electrochemical and tribological behaviors of the a-Cr coatings in the ionic liquid were investigated. Possessing high hardness, steady passive film, and few grain boundary structures, the a-Cr coatings exhibit much better corrosion and wear resistance compared with Fe, Cu, and nanocrystalline Cr coatings under the ionic liquid lubrication. © 2007 The Electrochemical Society. [DOI: 10.1149/1.2746129] All rights reserved.