Noise Temperature Research Articles

Atmospheric opacity correction in C-band at Irbene RT-16 radio telescope

The method (Kraus (2007)) for correcting atmospheric opacity in the C-band was applied to the RT-16 radio telescope of the Irbene observatory. The method is based on the calculation of the noise temperature T0, which is almost independent of the environment and is determined by the characteristics of the receiver and radio telescope antenna. T0 is determined using sky dip observations. The atmospheric opacity in the zenith is calculated using T0. We have determined the time dependence of T0 over a long period of time. It is shown that the T0 error increases the error of the flux density by no more than 0.5%.

Development of the Sanya Incoherent Scatter Radar and Preliminary Results

AbstractLed by the Institute of Geology and Geophysics, Chinese Academy of Sciences, we have built a brand‐new modular active digital phased array, with all solid‐state transmission and digital receiving incoherent scatter radar (ISR) in Sanya (18.3°N, 109.6°E), a station in low latitude China called Sanya ISR (SYISR) since 2015. The development of SYISR involved the indoor design and development of key components, an outdoor prototype test, and the production and debugging of the entire array. The unique features of SYISR include a single‐channel directly connected T/R unit and antenna, a radar array monitoring and calibration network, environmental adaptability design and open architecture. The entire radar has 4,096 channels and 5,930 modules in total. All the technical indices, mainly including a >2 MW peak power, a 43 dBi antenna gain and a <120 K noise temperature, either meet or are superior to the designed value through an independent evaluation. Waveforms of single pulse, linear frequency modulation, Barker code, long pulse and alternating code have been implemented to meet multiple purposes. Four observational modes for ionospheric experiments, including zenith stare, perpendicular to geomagnetic field, meridian scan, and all sky scan, have been developed. We have implemented time domain decoding, frequency domain decoding, and statistical inversion methods in calculating the autocorrelation function and power spectra in signal processing. The preliminary experimental results on ionospheric parameters, plasma lines, irregularities and hard targets are reasonable and encouraging, which greatly enhances our confidence in achieving our scientific goals in the future.

First results of collective Thomson scattering diagnostic of fast ions at the GDT open magnetic trap

Fast-ion diagnostic based on measuring of the collective Thomson scattering of high-power gyrotron radiation has been developed for the gasdynamic trap facility in Budker Institute during the last 3 years. This diagnostic is aimed at reconstruction of ion distributions over transverse and longitudinal velocities driven in the plasma core by strong neutral beam injection. Here, we present the first experimental results which may be interpreted as the expected scattering signal from fast ions. The detected spectra with the effective noise temperature of about 100 eV detuned in a particular frequency range of 100–300 MHz from the probe gyrotron frequency are compatible with the early theoretical predictions.

Taiwan axion search experiment with haloscope: Designs and operations.

We report on a holoscope axion search experiment near 19.6µeV from the Taiwan Axion Search Experiment with Haloscope collaboration. This experiment is carried out via a frequency-tunable cavity detector with a volume V = 0.234liter in a magnetic field B0 = 8T. With a signal receiver that has a system noise temperature Tsys ≅ 2.2K and an experiment time of about one month, the search excludes values of the axion-photon coupling constant gaγγ ≳ 8.1 × 10-14GeV-1, a factor of 11 above the Kim-Shifman-Vainshtein-Zakharov benchmark model, at the 95% confidence level in the mass range of 19.4687-19.8436µeV. We present the experimental setup and procedures to accomplish this search.

Statistical analysis of atmospheric parameters, noise temperature and digital terrestrial television signal strength over Jos metropolis, Plateau state, Nigeria

The study of the relationship between the Received Signal Strengths (RSS) from Unity TV (786 MHz) located at Rayfield (9.84 o North 8.89 o East), Jos, Plateau State and some atmospheric parameters with noise temperature has been done using two years half-hourly data. The measurement was carried from 5 am and 9 pm daily. The analysis was carried out using the regression, co-integration and Granger causality models. The results show that the RSS is higher in the morning hours (5.00 am–9.00 am) late in the evening (6.30 pm–9.00 pm) but lower between 9.00 am and 6.30 pm. This might be due to the “dusty” atmosphere and low reflection of ionosphere in the day time which causes signal attenuation within the day time. The correlation coefficients from the coefficient of determination (R squared) of 0.88, 0.004, 0.838. 0.25, 0.867, and 0.112, are −0.94, −0.07, 0.92, −0.50, −0.93, −0.334 for atmospheric temperature, pressure, relative humidity, wind speed, noise temperature and rainfall respectively. It means all the independent variables except relative humidity are inversely proportional with the RSS. Also, the higher R2 values for atmospheric temperature, relative humidity and noise temperature respectively, indicates higher correlation between RSS and these parameters. It can be inferred that the models are suitable for predicting Unity TV (UTV) signal strength and that of other TV stations in Jos and environs, using T, RH and NT as inputs. The results also showed that there is a co-integration and Granger Causal relationship between the parameters and RSS.The result will find applications to the Nigeria Broadcasting Commission in the assigning of frequencies taking atmospheric parameters into considerations, Radio Engineers and Scientists, Satellite link designers, and mobile communication experts for the link budget design and appropriate equipment deployment based on the atmospheric condition on the geographical areas.

ERRORS IN THERMAL IMAGERS TEMPERATURE RESOLUTION DETERMINING

Thermal imaging methods of environmental observation are often accompanied by the need to quantify the temperature distribution on the object’s surfaces. In such cases, the accuracy of modeling the information conversion processes that occur in thermal imaging systems is essential. All questions concerning the determination of thermal imagers temperature resolution are important. Experimental methods for determining temperature resolution in this sense are quite unambiguous and well-established in practice. And calculation methods are still being refined and are of interest to the scientific community.
 The article is devoted to the development of practical methods for calculating the thermal imagers temperature resolution. Such methods must be on the hand one accurate enough, and on the other hand - simple enough to be used in design organizations. The definition of the calculations error is also considered. The calculation model is based on the concept of equivalent noise temperature difference NETD as the most general characteristic of energy transformations in thermal imaging observations. The definition of NETD is based on the use of the thermal imager signal transmission function. A simplified version of the calculation method and an example of determining the temperature resolution for a thermal imager with a microbolometric matrix detector are presented. Such thermal imagers currently occupy a significant part of the market and the calculation of the characteristics of the device with a standard specification may be of interest to specialists. The influence of some elements of the mathematical information transformations model on the temperature resolution is shown. For example, as the background temperature increases, the temperature resolution decreases. The analysis of the proposed calculation model allowed us to outline ways to improve (reduce) temperature resolution. A feature of the developed methods is the possibility of their use for different thermal imaging systems, for example, for polarizing thermal imagers.

Influence of Spacer Thickness on the Noise Performance in InP HEMTs for Cryogenic LNAs

InP high electron mobility transistors (InP HEMTs) with different spacer thickness 1 to 7 nm in the InAlAs-InGaAs heterostructure have been fabricated and characterized at 5 K with respect to electrical dc and rf properties. The InP HEMT noise performance was extracted from gain and noise measurements of a hybrid low-noise amplifier (LNA) at 5 K equipped with discrete transistors. When biased for optimal noise operation, the LNA using 5 nm spacer thickness InP HEMTs achieved the lowest average noise temperature of 1.4 K at 4–8 GHz. The InP HEMT channel noise was estimated from the drain noise temperature which confirmed the minimum in noise temperature for the 5 nm spacer thickness InP HEMT. It is suggested that the spacer thickness acts to control the degree of real-space transfer of electrons from the channel to the barrier responsible for the observed noise variation in the cryogenic InP HEMTs.

Development of Quantum Limited Superconducting Amplifiers for Advanced Detection

Ultralow-noise microwave amplification and detection play a central role in different applications, going from fundamental physics experiments to the deployment of quantum technologies. In many applications the necessity of reading multiple detectors, or cavities or qubits, calls for large bandwidth amplifiers with the lowest possible noise. Current technologies are based on High Electron Mobility Transistors and Josephson Parametric Amplifiers. Both have limitations, the former in terms of the minimum noise, the latter in terms of bandwidth. Superconducting Traveling Wave Parametric Amplifiers (TWPAs) have the potential of offering quantum limited noise and large bandwidth. These amplifiers are based on the parametric amplification of microwaves traveling along a transmission line with embedded nonlinear elements. We are developing superconducting TWPAs based both on Josephson junction arrays (Traveling Wave Josephson Parametric Amplifiers) and on nonlinear kinetic inductance (Dispersion Engineered Traveling Wave Kinetic Inductance Amplifiers). Our goal is to achieve large bandwidth (in the 5 to 10 GHz range), large gain (more than 20 dB), large saturation power (more than −50 dBm), and near quantum limited noise (noise temperature less than 600 mK). Current achievements in the design and development of the high performance TWPAs are here reported and discussed, together with current limitations and possible future developments.

Multi-Level Approximations for Fast and Accurate Antenna Noise Temperature Calculation of Dual-Reflector Antennas

Antenna noise temperature calculation for a reflector antenna system can be a computationally expensive operation if the structure is electrically large. Several approximate methods have been suggested to speed up the calculation. These rely on removing one or more of the reflecting surfaces from the calculation domain and compensating for the effect through geometric optics arguments. This article presents a unified multilevel approximation formalism, which allows the user the freedom to tradeoff the simulation time, implementation complexity, and result accuracy as required for a specific application. As part of the formalism, a strategy to reliably remove both reflectors in a dual-reflector system from the calculation domain and rely on ray tracing to correct the background temperature is developed. It is shown that this new method reduces calculation time by several orders of magnitude while maintaining accuracy in the final antenna temperature result of the order of 1%. It is fast and accurate enough to be used in numerical optimization loops. The method requires the implementation of a ray tracing algorithm, and thus, may present some unnecessary complexity if only rough temperature estimates are required. To this end, a simplified method is also presented requiring no ray tracing and only simple postprocessing of readily available feed pattern data. Though not as accurate as of the ray tracing-based method, temperatures may be estimated with around 10% accuracy over bandwidths well in excess of a decade.

Thermal Noise Measurements in a Reverberation Chamber

Two models describing properties of the thermal noise power emerging from an antenna mounted in a reverberation chamber are described. The first compares the reverberation chamber to an over-molded cavity acting as a black-body source; the second describes the noise in terms of the antenna noise temperature. Measurements based on the antenna noise temperature model show the noise power to be dependent on the position of the rotating mechanical stirrer. The correlation of the antenna noise temperature with the stirrer position-dependent antenna mismatch factor is shown. When a signal is injected into the chamber measurements of the signal to noise power ratio show that this ratio is dependent on the stirrer position and also the position of the signal source within the chamber. These results have significant consequences for the detection of weak signals from radiating sources in a reverberation chamber.

SOCIALIZATION OF SORT, STRAIGHTEN, SHINE, STANDARDIZE, SUSTAIN (5S) FOR UD. TIRTO AGUNG GRESIK

Occupational Health and Safety (OHS) is important in all industrial sectors. The purpose of Occupational Health and Safety (OHS) is to improve and maintain the highest degree of all workers, both physically and mentally, and to ensure workers' welfare to prevent occupational diseases. UD. Tirto Agung is an informal industry that produces various types of cotton. UD. Tirto Agung Worker has 13 employees consisting of 7 women and six men divided into two work shifts. The practitioner's survey observed various potential hazards, namely noise, dust, poor lighting, and bad air temperature. From this problem, practitioners provide education about 5S (Sort, Straighten, Shine, Standardize, Sustain). This socialization aims to provide insight and knowledge about the 5S program, dust hazards, and practitioners providing personal protective equipment (PPE). The socialization results are successful because knowledge of Occupational Health and Safety (OHS) has increased from 13 workers, 10 of whom understand the dangers in the work environment and can implement 5S socialization in the workplace. In comparison, three workers have yet to be able to implement 5S in the work environment due to the influence of age.

0423 Associations of individual behaviors and ambient factors in the sleep environment with nighttime sleep parameters in pregnant women with insomnia

Abstract Introduction Sleep hygiene and environment are important for adequate sleep quantity and quality. We examined two aspects of the sleep environment, individual behaviors and ambient factors, with nighttime sleep parameters in pregnant women with insomnia. Methods We used baseline data from a randomized controlled trial of insomnia treatment during pregnancy for this cross-sectional analysis (n=70). Women completed a questionnaire assessing whether they regularly engaged in five individual behaviors in bed (yes/no) and how much their sleep was disrupted by seven ambient factors (scale from 1=not very much to 5=very much) and wore an Actiwatch 2 for a subsequent 7-day period. Responses of 4 or 5 for ambient factor items were categorized as ambient factors perceived to disrupt sleep. Generalized estimating equation regression models were used to estimate associations of individuals behaviors and ambient factors perceived to disrupt sleep with actigraphy-measured total nighttime sleep duration and sleep efficiency. Results The most commonly endorsed individual behaviors were using the internet/computer in bed (64%) and watching television in bed (43%), followed by talking on the phone in bed, listening to music in bed, and playing video/electronic games in bed (16-27%). Watching television in bed was associated with 23 fewer minutes of actigraphy-measured nighttime sleep (95% CI: -44, -1). No individual behavior was associated with actigraphy-measured sleep efficiency (all P>0.05). The most commonly endorsed ambient factors perceived to disrupt sleep were environmental noise (41%) and uncomfortable temperature (37%), followed by movement from others sharing the bed, having to take care of children in the middle of the night, someone else snoring, and light (24-29%). No ambient factors perceived to disrupt sleep were associated with actigraphy-measured nighttime sleep duration or efficiency (all P >0.05). Conclusion Individual behaviors and ambient factors perceived to disrupt sleep were common in pregnant women with insomnia. In this study, only watching television in bed was associated with objectively-measured nighttime sleep duration. Our findings suggest that future research could investigate potential interfering roles of arousal and cognitive factors contributing to insomnia during pregnancy. Support (If Any) National Institutes of Health (K99HD100585, R01NR013662)

ASTE Band 10 (787–950 GHz) heterodyne receiver: System description, commissioning, and science verification

Abstract We report the system description and results of the commissioning and science verification (CSV) of the Band 10 (787–950 GHz) heterodyne receiver for ASTE (Atacama Submillimeter Telescope Experiment), a 10 m submillimeter telescope at the ALMA (Atacama Large Millimeter/submillimeter Array) site in Chile. The new ASTE Band 10 receiver cartridge was refurbished from a prototype ALMA Band 10 receiver with SIS mixers employing high critical current density junctions. We installed the new receiver on ASTE and carried out its CSV. The best double-sideband (DSB) system noise temperature achieved on ASTE toward the zenith was ∼1500 K (PWV ∼ 0.5 mm). As a part of CSV activities, we performed science verification observations to demonstrate ASTE Band 10 capabilities to the community. Wide-field images were successfully obtained toward the well-studied OMC-1 region with both [C i](3P2–3P1) and 12CO(J = 7–6) lines. In addition, we partially carried out observations toward a super star cluster RCW 38, [C i](3P1–3P0), images of which were already obtained by ASTE. We demonstrated the capability of ASTE Band 10 observations toward bright and extended objects like giant molecular clouds.

Noise and Conversion Analyses for High-T c Superconducting Harmonic Mixers: Theoretical Modeling and Experimental Verification

High- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> superconducting (HTS) harmonic mixers are attractive frontends for terahertz wireless communication and sensing applications. However, the investigation of HTS harmonic mixers has long been hindered by the lack of effective theoretical method in device modeling. This article presents a modeling approach for analyzing the noise and conversion properties of HTS harmonic mixers. By quantitively analyzing the contribution of the parasitic components to frequency conversion, a parasitics-selection based equivalent circuit model is built with the architecture complexity reduced to a six-port network. Besides, a fast hybrid-solution method that combines the single-tone current excitation and perturbation-derivation processing techniques, is developed for efficiently calculating the conversion impedance matrix for harmonic mixing. Detailed derivations are then carried out to acquire the semianalytic expressions of noise temperature and conversion gain after solving the noise correlation matrix for harmonic mixing. The presented modeling method has been verified by the fourth harmonic mixing experiments for a dual-band antenna-coupled HTS Josephson-junction mixer module. The measured and simulated results are in good agreement in terms of the noise temperature and conversion gain as well as their dependance on dc biasing, local oscillator pumping, and operating temperatures. The results have validated the effectiveness of the presented modeling method for analyzing the properties of HTS Josephson junction mixers.

A highly directional eight‐hole coupling circular waveguide coupler

Aiming at the system noise temperature calibration of the K-band seven-beam cryogenic receiver on Tianma Radio Telescope, a design of K-band highly directional coupler is proposed in this paper. Based on the hole coupling principle proposed by Gian Guido Gentili, an eight-hole coupling circular waveguide directional coupler is designed by ANSYS HFSS software. Through the distribution mode of eight coupling holes, the excellent performance and compact structure have been realized. Measurement shows that the reflection coefficient is less than −25 dB, coupling degree is stable within −25 ± 1 dB, isolation degree is lower than −35 dB, and directivity coefficient is greater than 10 dB in its operating frequency range.

Phase diffusion and noise temperature of a microwave amplifier based on single unshunted Josephson junction

High-gain microwave amplifiers operating near quantum limit are crucial for development of quantum technology. However, a systematic theoretical modeling and simulations of their performance represent rather challenging tasks due to the occurrence of colored noises and nonlinearities in the underlying circuits. Here, we develop a response theory for such an amplifier whose circuit dynamics is based on nonlinear oscillations of an unshunted Josephson junction. The theory accounts for a subtle interplay between exponentially damped fluctuations around the stable limit cycle and the nonlinear dynamics of the limit cycle phase. The amplifier gain and noise spectrum are derived assuming a colored voltage noise at the circuit resistor. The derived expressions are generally applicable to any system whose limit cycle dynamics is perturbed by a colored noise and a harmonic signal. We also critically assess reliabilities of numerical methods of simulations of the corresponding nonlinear Langevin equations, where even reliable discretization schemes might introduce errors significantly affecting simulated characteristics at the peak performance.

Delayed elastic contributions to the viscoelastic response of foams.

We show that the slow viscoelastic response of a foam is that of a power-law fluid with a terminal relaxation. Investigations of the foam mechanics in creep and recovery tests reveal that the power-law contribution is fully reversible, indicative of a delayed elastic response. We demonstrate how this contribution fully accounts for the non-Maxwellian features observed in all tests, probing the linear mechanical response function. The associated power-law spectrum is consistent with soft glassy rheology of systems with mechanical noise temperatures just above the glass transition [Fielding et al., J. Rheol. 44, 323 (2000)] and originates from a combination of superdiffusive bubble dynamics and stress diffusion, as recently evidenced in simulations of coarsening foam [Hwang et al., Nat. Mater. 15, 1031 (2016)].

Prediction of Indoor Environmental Quality Using a Regression Model for Educational Buildings in Hot Arid Climate: A Case Study in the Al-Najaf Technical Institute – Iraq

In hot climates, achieving a good indoor environmental quality (IEQ) in existing buildings is important especially with climate change challenges as future heat waves will increase in frequency, duration, and intensity. In educational buildings, there is much more focus on the IEQ parameters and the interactions among them that need to be in line with the continuously changing learning environment. This study assesses the IEQ parameters (represented by noise, temperature and humidity) at three selected campus areas (lecture rooms of an administrative department building (LR), main hall of a management department building (MH) and a central library building (CL)) at the Al-Najaf Technical Institute (NTI), Al-Najaf City, Iraq, for the period from May to December 2019. A statistical analysis using a multi-linear regression model was performed to determine the relationship between the selected IEQ parameters and explain the noise level behavior as a function of the temperature and relative humidity. The research indicated that the noise levels and temperature values exceeded the maximum standard limits in all buildings reflecting the displeasing sound and heating quality within the studied areas, while the readings for relative humidity within each building environment complied with standards. Moreover, for both LR and MH buildings (R2 ≥ 0.8, significance F ≤ 0.01), the noise values were satisfactorily modeled by temperature and relative humidity highlighting the interactions between temperature, humidity and noise under consistent conditions. However, the results for the CL building (R2 = 0.6, significance F = 0.1) showed no relationship between the IEQ parameters, highlighting the fact that this building is exposed to unsteady conditions (an irregular number of people using this building during the daytime) resulting in a high variation of data measurements. The current results demonstrate that detailed modeling can be helpful to predict IEQ parameters depending on other known parameters in buildings. The results of the predictive model aligned with the directly measured data. Therefore, its performance is equally effective, but with a significant reduction in cost and time consumed.

Multimode Physics in the Mode Locking of Semiconductor Quantum Dot Lasers

Quantum dot lasers are an attractive option for light sources in silicon photonic integrated circuits. Thanks to the three-dimensional charge carrier confinement in quantum dots, high material gain, low noise and large temperature stability can be achieved. This paper discusses, both theoretically and experimentally, the advantages of silicon-based quantum dot lasers for passive mode-locking applications. Using a frequency domain approach, i.e., with the laser electric field described in terms of a superposition of passive cavity eigenmodes, a precise quantitative description of the conditions for frequency comb and pulse train formation is supported, along with a concise explanation of the progression to mode locking via Adler’s equation. The path to transform-limited performance is discussed and compared to the experimental beat-note spectrum and mode-locked pulse generation. A theory/experiment comparison is also used to extract the experimental group velocity dispersion, which is a key obstacle to transform-limited performance. Finally, the linewidth enhancement contribution to the group velocity dispersion is investigated. For passively mode-locked quantum dot lasers directly grown on silicon, our experimental and theoretical investigations provide a self-consistent accounting of the multimode interactions giving rise to the locking mechanism, gain saturation, mode competition and carrier-induced refractive index.

Tobacco Use among Workers in a Foundry Unit of North Karnataka

Background: Foundry workers are the backbone of many industries. Workers are exposed to metal dust, metal fumes, various products of combustion, chemical products relating to resin compounds, and physical factors such as noise, vibration, and high temperature. In addition to these factors, the use of tobacco, especially smoking, may aggravate health hazards, mainly respiratory morbidities. Objective: To know the prevalence of tobacco use among workers in a foundry unit of North Karnataka. Method: It was a cross-sectional study conducted among 300 workers of a foundry unit in North Karnataka from July to September 2019. Every second worker from the attendance register was selected for the study. The questionnaire was adopted from Global Adult Tobacco Survey (GATS). Data were collected by personal interview after informed consent. Data were analysed through descriptive statistics and Chi-square test. The study was approved by Institutional Ethics Committee.Results: The mean age of participants was 38.73 ± 10.13 years. The prevalence of tobacco use in any form was found to be 42.66%. The smokeless form was predominant. Tobacco use was significantly associated with years in present occupation and night shifts. Conclusion: The prevalence of tobacco use among workers of a foundry unit was high which calls for immediate focused interventions.