Linear Transmittance Research Articles

ISO 10211 전열해석을 통한 경량목구조의 주요 구조부 단열성능 데이터베이스 구축

This study aimed to establish a thermal performance database for various lightweight wood-frame house envelopes in order to increase the accuracy of insulation assessment and energy performance analysis for lightweight wood-frame buildings. The differences in energy and insulation performances were analyzed based on the thermal transmittance calculation method for composite walls. The linear thermal transmittance (<TEX>${\Psi}$</TEX>), equivalent thermal transmittance (Ueq), and thermal conductivity of various composite walls for lightweight wood-frame houses were calculated. PHYSIBEL Trisco V.12 was used for the heat transfer analysis, and DesignBuilder V.3.4 was used for the energy performance analysis. The thermal transmittance in the case studies was compared with the heat transfer analysis, and the results confirmed a difference of 3.8%-22.7% for the thermal transmittance and a difference of 3.2%-12.1% for the heating energy. When heat transfer analysis was conducted for various configurations of the lightweight wood-frame house such as the stud spacing, stud thickness, stud placement, and presence of an airtight layer, the results showed a linear thermal transmittance (<TEX>${\Psi}$</TEX>) difference that was approximately 4.8 times depending on the wall configuration. The thermal conductivity (<TEX>${\lambda}$</TEX>) of the inversion stud and insulation layer was <TEX>$0.0433-0.0492W/m{\cdot}K$</TEX>, indicating a maximum of 11.9% on the stud interval of 406 mm (16 in) and <TEX>$0.0404-0.0452W/m{\cdot}K$</TEX> indicating a maximum of 10.6% on the interval of 610 mm(24 in). With the database established in this study, the thermal performance of the composite walls in lightweight wood-frame houses can be calculated without a complex heat transfer analysis and can be used as basic data for the construction of eco-friendly low-energy wooden structures.

Prediction of thermal transmittance for lightweight wood-frame houses using hierarchical regression analysis

This study aims to establish a prediction equation for the thermal transmittance of the thermal bridges in a lightweight wood-frame house comprising composite wall materials using a statistical method. A heat transfer analysis was performed on 288 cases with different independent variables that affect the linear thermal transmittance and equivalent thermal transmittance of a wooden structure, and independent variables with a high degree of influence were selected through hierarchical regression analysis in order to establish a regression equation. The predicted values were compared with the heat transfer analysis values for verification. The results showed an average error of 5.9% and maximum error of 15.1% for the linear thermal transmittance and an average error of 0.9% and maximum error of 3.0% for the equivalent thermal transmittance, demonstrating an engineering level of reliability ( < 10%). The results of this study contribute to improving the rapidity and accuracy of assessing the energy performan...

A Study of the Impact of Delay Mismatch on Linearity of Outphasing Transmitters

This paper presents an analytical study of the impact of delay mismatch on the linearity of outphasing transmitters. Analytical expressions are derived to quantify the impact of delay mismatch between the two amplifying paths on the adjacent channel power ratio and error vector magnitude of any complex modulated output signal. These expressions can be used to specify delay mismatch for any given requirement of linearity performance of an outphasing transmitter. A complete LTE transceiver physical layer model in simulink is used to simulate the whole transceiver chain. An embedded model of an outphasing transmitter with a variable delay mismatch is included to compare error vector magnitude simulation data with theoretically derived results for different LTE downlink channels of 1.4 MHz, 10 MHz and 20 MHz channel bandwidths. Outphasing signals are synthesized with different delays and uploaded to a vector signal generator such that adjacent channel power ratios can be measured. This allows for a comparison between hardware-probed results and the theoretical calculations for LTE channels of 1.4 MHz and 10 MHz channel bandwidths.

Nonlinearity suppression of Mach–Zehnder modulator based on optical carrier processing in radio-over-fiber links

A highly linear transmitter that consists of a dual-drive Mach–Zehnder modulator (DD-MZM), an optical gain, and an optical phase shifter in radio-over-fiber links is proposed and demonstrated by simulation. The optical carrier is split equally with one part driving the DD-MZM, while the other part remaining unmodulated. By properly adjusting the magnitude and phase shift of unmodulated optical carrier, two kinds of main origins of third-order IMD (IMD3) have equal intensity and opposite phase, and cancel each other out. The comparison of the proposed technique and double-sideband modulation by MZM is presented. Simulation results shown that the spurious-free dynamic range of 125.3 dB Hz2/3 is achieved, which is about 26 dB more than a quadrature biased MZM.

Concurrent Multi-Band Envelope Modulated Power Amplifier Linearized Using Extended Phase-Aligned DPD

This paper reports an envelope tracking (ET) transmitter architecture for multi-band/widely-spaced carrier signals. Due to the bandwidth limitations of the envelope modulator, the dynamic supply voltage is controlled by combining the low frequency envelopes of the multi-inputs rather than the true composite envelope of the input signals. The ET transmitter is tested for dual-band and tri-band power amplifiers (PAs) operating in concurrent mode using various bandwidth carrier aggregated long term evolution (LTE) signals. The transmitter is linearized using a phase-aligned Volterra digital predistortion that considers the inter-modulation distortion (IMD) products around the carrier frequencies as well as the third-order IMD products in the tri-band case. Experimental results are shown to validate the proposed techniques for linearization and efficiency enhancement of the multi-band ET transmitter and compared to the case of fixed supply biasing of the PA.

Computation of linear transmittance of thermal bridges in precast concrete sandwich panels

Precast concrete lightened sandwich panels are widely used building elements. They are made by two concrete wythes separated by a layer of lightweight material: the central layer is inhomogeneous due to the presence of concrete ribs which tie the external wythe and act as thermal bridges.Computation of thermal transmittance of sandwich panels is clearly described in European Standards, but in many cases it requires numerical simulations to determine the linear transmittance ψ associated with lightweight material-concrete interfaces in the inhomogeneous layer. Although simple, these simulations represent a critical issue for many panel manufacturers and they would much rather prefer correlations to compute ψ.In this work we present a correlation based on an artificial neural network (ANN) to estimate linear trasmittauce values for current Italian sandwich panel production. Five input parameters are considered: rib width, lightweight material conductivity, and thickness of the three panel layers. To obtain the data which are necessary to train and test the ANN, a fast and accurate Spectral Element Method is used to solve Laplace equation in the neighborhood of a rib. 5460 ψ values are collected which ensure an accurate network response.

Determination of Linear Thermal Transmittance for Corners with Acute Angle

This paper deals with the determination of linear thermal transmittance for buildings with acute angle shapes. Calculation of linear thermal transmittance is a standard problem in determining the influence of thermal bridges on the overall energy performance of buildings. Computational methods are known for ordinary rectangular buildings and the values of typical detail are listed in databases. Current architecture of designs buildings uses acute angle shapes quite frequently. It corresponds with new trends in architecture. In such cases the value of linear thermal transmittance is not accurate for using databases. This paper presents an analysis of the influence of the change of angle of the walls in corner to linear thermal transmittance. It provides information applicable for buildings assessment in engineering practice.

Transient Numerical Simulation of Linear Thermal Transmittance in Software CalA

Calculation of heat losses of buildings according to European standard EN ISO 10211 and Czech standard ČSN 73 0540 is simplified to one-dimensional time-steady heat conduction through the building construction in direction of the largest temperature gradient. This simplification of the calculation is incorrect in case of complex geometry. Calculation according to norm takes into account this inaccuracy and uses Linear Thermal Transmittance Ψ [W/(m·K)] in 2D geometry or Point Thermal Transmittance χ [W/(m2·K)] in the 3D geometry as a calculation correction. This contribution is focused on detailed calculation of linear thermal transmittance in case of contact external peripheral wall and plastic window frame. Results of two-dimensional transient numerical simulation show unsteady linear thermal transmittance in time and dependence on solar radiation. All of these variable boundary conditions can be easily simulated in the software CalA as well as complex geometry.

Feedback Linearization of RF Power Amplifier for TETRA Standard

In wireless transmission systems, non-ideal response of different functional components along with power amplifier’s nonlinearity plays a major role in degrading the transmitter performance. Several parameters defines the performance of a wireless transmitter, such as adjacent channel power ratio (ACPR), error vector magnitude (EVM), spectral mask, etc., and the effect of non-ideal behaviour of the transmitter affects these parameters. For many standards these parameter specifications are defined such that the concern for transmitter linearization is very much relaxed. Standards like Terrestrial Trunked Radio (TETRA) specify strict regulation on these parameters. Therefore, the requirement of linearity is a great challenge for the design of the transmitter. Many linearization schemes is available for linearizing the nonlinear effect of a transmitter, and among those the Cartesian feedback technique is a well known concept for linearization of transmitter operating according to TETRA standard, as well as employing a narrowband operation. In our research, distortion effect of the transmitter has been analysed, and a practical demonstration of the linearization effect over distortion has been implemented using the Cartesian feedback concept.

Influence of doping level on the structure, texture, and nonlinear optical properties of graphene oxide/Au hybrids doped ORMOSIL gel glasses

Graphene oxide (GO)/Au nanoparticle (NP) hybrids were introduced into nanostructured sol–gel organically modified silica (ORMOSIL) using a sol–gel technique. Scanning electron microscopy, Raman spectroscopy, thermogravimetric analysis, pore structure measurements, and UV–vis spectroscopy were performed to investigate the morphology, structure, texture, thermal stability and linear optical properties of the ORMOSIL gel glasses. The guest two-dimensional GO/Au NP hybrids maintained their own structures during the sol–gel procedure, confirming that the sol–gel technique can effectively produce graphene-based solid-state bulky composites. Increasing doping level would result in the formation of a highly porous structure, better thermal stability, and lower linear transmittance. The nonlinear optical (NLO) properties of GO/metal NP-doped ORMOSIL gel glasses were investigated using a nanosecond open-aperture Z-scan technique at 532nm. The nonlinear absorption coefficient of GO/Au NP-doped ORMOSIL gel glasses increases from 3.79cm/GW to 8.79cm/GW with increased doping level from 4.8×10−3 to 19.2×10−3. The result demonstrates that the NLO performance of the composite ORMOSIL gel glasses can be optimized by tuning the doping level of 2D GO/Au NP sheet in the matrices of the host gel glasses. The NLO behavior of GO/Au NP-doped ORMOSIL gel glasses were attributed to the combination of nonlinear absorption and nonlinear scattering.

전열해석 시뮬레이션을 통한 패시브주택의 단열외피 열교 최소화 상세 개발 연구

Current Korean building energy policy and standards provide only the specific insulating performance standards of the building component and it overlooks the prevention of heat loss caused by thermal bridge when evaluating building performance. In this research, details to minimize the heat loss due to thermal bridge was developed to achieve the linear thermal transmittance criterion(Psi<0.01W/mK) of the German Passivhaus Institut(PHI), performed through two-dimensional heat transfer simulation in a steady-state-condition (ISO 10211:2007). Then, the heat loss from the developed passive house details was compared with the exampled details as per the current Korean building code, and their effect on the annual heating energy demand was weighed according to the calculation method in PHPP(the building energy performance evaluation program of the PHI). Lastly, the possibility of condensation and mould was evaluated by using the temperature factor (ISO 10211:2007). As the result, while the overall heat loss through thermal bridges in enhanced passive house details was minimized to <TEX>$1.1kWh/m^2a$</TEX>, the gross heat loss due to thermal bridge in exampled details was <TEX>$35.3kWh/m^2a$</TEX>, which exceeds alone the annual heating energy demand criterion (<TEX>$15kWh/m^2a$</TEX>) for passive house set by PHI. This shows that enhancing the building energy performance to the high-energy-efficient standard will be hindered, if minimizing thermal bridge is left neglected. Therefore, it is necessary to set up specific criteria to minimize the heat loss due to thermal bridge, in order to achieve the Korean building energy-efficiency road map set by the government. In addition, the study for diverse measure to manage the thermal bridge details in design and construction process is needed.

Leveraging Integration: Toward Efficient Linearized All-Silicon IC Transmitters

Recent efforts in efficient linearized all-Si IC transmitters have produced a 7x increase in output power and a +15% increase in PAE (over the 2008 PAE state of the art of 20%) of integrated Si mm-wave PAs. A number of on-chip integrated, highly linear transmitter architecture approaches have been developed and demonstrated.

DWT-IDWT-based MB-OFDM UWB with digital down converter and digital up converter for power line communication in the frequency band of 50 to 578 MHz

Over the last few years, power line communication (PLC) has gained importance for high-speed data communication. One of the major concerns in PLC is noise and high data rate, thus, several schemes have been adopted to minimize noise over PLCs and improve data rate. One of the promising approaches is the use of multi band (MB)–orthogonal frequency division multiplexing (OFDM) ultra wideband (UWB) to achieve date rates over 200 Mbps. One of the approaches is to integrate MB-OFDM UWB with digital down converter (DDC) for power line communication. A modified discrete wavelet transform (DWT) architecture with reduced memory, two-stage DDC, and modified DDS blocks are designed to generate MB-OFDM signal for PLC. From the results obtained, it is found that DWT-based MB-OFDM UWB outperformed FFT-based MB-OFDM UWB by approximately 6-dB gain in bit error rate (BER). Haar wavelet showed best performance over Biorthogonal (bior3.3, bior5.5), Daubechies (db2, db4), and reverse Biorthogonal (rbior3.3, rbior5.5) by approximately 2 dB. Though QPSK yielded better BER through observations, it is used for a constant power output transmitter, while QAM works better for a linear transmitter.

Numerical examination of thermal bridging effects at the edges of vacuum-insulation-panels (VIP) in various constructions

The thermal losses on the edges of vacuum insulation panels (VIP) are influenced by the thickness of the panels, the type of edge design (single- or multi-layered foils), the inorganic barrier material and the thickness of the barrier layers. Additional thermal bridging effects result from applications and constructions, e.g., the material used in the joint between two panels (e.g. elastomeric foam), the covering layers on the panels and the mechanical fasteners used for mounting and fixing. Via numerical simulations for VIP of varying thickness, the thermal bridging effects are determined for different influencing factors. The impact of the linear thermal transmittance on thermal resistance of panels of various sizes is calculated and equivalent thermal conductivity of the panels determined.

Third-order optical nonlinearity of Na2O–B2O3–SiO2 glass doped with lead nanoparticles prepared by sol–gel method

Lead-nanoparticles-doped Na2O–B2O3–SiO2 (NBS) glass was prepared by sol–gel and atmosphere control methods. The formation mechanism and the microstructure of the specimens were investigated by differential thermal analysis and thermal gravimeter, X-ray diffraction, transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy, and nitrogen adsorption measurements, respectively. The linear and nonlinear optical properties of the glass were analyzed by UV/VIS/NIR spectrophotometry and Z-scan technology. The results showed that the Pb nanoparticles in spherical shape with the average particle size about 18.9nm belong to cubic crystal system and have good crystallinity and dispersibility in the glass matrix as well as exhibit excellent nonlinear optical properties. The specimen has a high linear optical transmittance, and little absorption peaks appear in the examined wavelength range. The third-order optical nonlinear parameters calculated are γ of 1.67×10−16m2/W, β of 7.02×10−11m/W, and χ(3) of 2.61×10−17m2/W2.

Determination of Linear Thermal Transmittance for Curved Detail

This paper deals with the determination of linear thermal transmittance for buildings with rounded shapes. Calculation of linear thermal transmittance is a standard problem in determining the influence of thermal bridges on the overall energy performance of buildings. Computational methods are known for ordinary rectangular buildings. Current energy-saving architecture designs buildings with rounded organic shapes quite frequently. Not only it corresponds with new trends in architecture, but also serves to improve the area to volume ratio of buildings. In such cases the value of linear thermal transmittance calculated by standard methods isn't accurate enough. This paper presents an analysis of the influence of the curvature of the buildings surface to linear thermal transmittance. It provides information applicable for buildings assessment in engineering practice.

The effect of pump depletion on reversible photodegradation

We model the effect of pump depletion on reversible photodegradation using the extended domain model [Anderson and Kuzyk, arXiv:1309.5176v1, 2013] and the Beer–Lambert law. We find that neglecting pump absorption in the analysis of the linear optical transmittance leads to an underestimate of the degree and rate of photodegradation. The model is used to accurately measure the molecular absorbance cross sections of the three species involved in photodegradation of disperse orange 11 dye in (poly)methyl-methacralate polymer (DO11/PMMA). Finally we find that the processing history of a dye-doped polymer affects reversible photodegradation, with polymerized monomer solutions of DO11 being more photostable than those prepared from solvent evaporated dye-polymer solutions.

Novel Real-Time Closed-Loop Device Linearization via Predictive Pre-Distortion

In this paper, a novel real-time closed-loop device linearization technique has presented. In this paper the focus application is on AM/AM and AM/PM linearization of power amplifiers (PA) and/or radio transmitters. In such an application, the novel approach performs on-the-fly measurement-and-prediction of the nonlinear characteristics of the PA, stores such non-linear characteristics and calculates their inverse functions in order to pre-distort the base-band amplitude and phase signals modulating the PA such that the combination, or the resultant, of the pre-distorter and the PA leads to a linear behavior at the output of the PA. The predictive nature of the presented approach overcomes the inevitable delay between the time a measurement is collected through the feedback loop and the time it has taken place at the output of the forward loop, which is a must-have delay encountered in any natural causal system. Such a delay results in imperfect on-the-fly pre-distortion of the output signal due to the mismatch between the applied pre-distortion, which has been based on a past measurement, and the actual effect of the non-linearity at the time the signal is produced [5]. In addition, this novel approach promises the advantage of operating a highly non-linear (compressed) PA - hence, highly efficient - with minimal factory pre-calibration. We present a model of our predictor based approach and evaluate its performance for a GSM/EDGE/UMTS a cellular transmitter scenario, where the performance requirements on the transmitted signal are stringent and distortion due to non-linearity must be minimized. The key performance metrics we evaluate have mostly been based on the GSM/EDGE/UMTS requirements, such as the Error Vector Magnitude (EVM), Switching Transients (ST), and Adjacent Channel Power Ratio (ACPR), transmit time mask, modulation spectrum and power-added efficiency (PAE). Although the focus of the numerical results in this paper is on the GSM/EDGE/UMTS application, the novel approach discussed is applicable to any TDMA or TDD system where switching transients and spectral performance is tightly controlled.

A Low-Noise Delta-Sigma Phase Modulator for Polar Transmitters

A low-noise phase modulator, using finite-impulse-response (FIR) filtering embedded delta-sigma (ΔΣ) fractional-N phase-locked loop (PLL), is fabricated in 0.18 μm CMOS for GSM/EDGE polar transmitters. A simplified digital compensation filter with inverse-FIR and -PLL features is proposed to trade off the transmitter noise and linearity. Experimental results show that the presented architecture performs RF phase modulation well with 20 mW power dissipation from 1.6 V supply and achieves the root-mean-square (rms) and peak phase errors of 4° and 8.5°, respectively. The measured and simulated phase noises of −104 dBc/Hz and −120 dBc/Hz at 400-kHz offset from 1.8-GHz carrier frequency are observed, respectively.

Investigation of optical nonlinearity and diffraction ring patterns of carbon nanotubes

Abstract The third order nonlinear optical properties of multi-wall carbon nanotubes (MWNT), single-wall carbon nanotubes (SWNT) dissolved in 1,2-dichlorobenzene and SWNT doped poly(ethylacetylenecarboxylate) polymer have been studied using Z-scan technique. Experiments are performed using a CW diode laser at 635 nm wavelength with 26 mW power. It has been found that the values of nonlinear absorption coefficient β, nonlinear refractive index n2, Re χ3, and Im χ3 in SWNT are larger than in MWNT. It was noticed that the closed-aperture Z-scan is most effective when the linear transmittance of the aperture “S” is small. Laser-induced diffraction ring patterns were observed only for SWNT. Based on the number of diffraction rings, variation of refractive index Δn and the relative phase shift ∆ϕ(r) have been estimated at different input laser power: 5, 10, 15 and 25 mW.