Influence of Temporal- and Spatial Resolutions on Building Performance Simulation Models: A Danish Residential Building Case Study

This study aims to assess the accuracy of a building performance simulation (BPS) model developed in IDA ICE software, focusing on heating energy use and indoor air temperatures in a low-energy multi-story residential building located in Northern Denmark. Six apartments were analyzed, and a comparative analysis was conducted between the measured parameters and the results obtained from BPS models with different spatial and temporal resolutions. The findings indicate that while the BPS models can provide reasonably accurate estimates of heating energy use, they may not fully capture the nuanced response to factors such as indoor air temperature This highlights the importance of incorporating qualitative inputs and environmental variables into these BPS models, including heating and/or cooling setpoints, internal gains, and weather conditions. Overall, this study provides insights into the limitations and opportunities of BPS models for accurately estimating heating energy use and indoor air temperatures in low-energy residential buildings

Rebirth of Lithuanian Jewish (Litvak) culture in present-day Lithuania : construction or deconstruction

The article constitutes a discussion of the rebirth of Lithuanian Jewish (Litvak) culture that is taking place in the country since the last decade. It is a wide and diverse phenomenon containing different aspects of social and cultural life, revealing itself in various domains of the academic and public spheres. The rebirth sparks a heightened interest in Litvak history, culture, religion, art, problems of Lithuanian and Jewish interaction - all this within the cultural domain of the Grand Duchy of Lithuania. To analyze these problems, various groups of scholars are emerging, libraries or departments of libraries are being established, new books are being published, conferences are being organized, special lectures are being held at universities - all this adds up to the rebirth of Litvak culture in the academia

Kompaktiškų spektroskopinių terahercinių vaizdų fiksavimo sistemų vystymas ir taikymas naudojant optinio pluošto inžinerijos principus

The dissertation objective was to investigate and improve terahertz (THz) imaging techniques allowing for inspection of hidden objects without harmful X-rays. The work was carried out as follows. Firstly, an efficient and cost-effective compact homodyne THz imaging scheme was developed using reliable bow-tie diodes as an alternative to heterodyne THz imaging technique for low absorbing object identification using paper sheets for phase shifting at 0.3 THz and 0.6 THz frequencies. Secondly, effect of molecular beam epitaxy growth conditions on InGaAs/InP layers dedicated for bow-tie diodes fabrication was investigated and optimal growth regime with respect to InGaAs diodes parameters was determined. Furthermore, silicon diffractive optics-based Fibonacci bifocal THz lens was designed, fabricated and investigated. Additionally, the designed bifocal THz lens was applied for THz imaging, demonstrating simultaneous multi-focal THz imaging. Moreover, diffractive THz lens allowing Bessel THz imaging was developed with extended focal depth up to 20 mm suitable for imaging of objects hidden in post packages. Additionally, purely silicon optics based Bessel THz imaging was demonstrated and deconvolution algorithms were applied for enhancement of the contrast. Finally, THz beam manipulation using spatial filtering methods was investigated and applied for THz imaging revealing its advantages in comparison with other beam engineering methods

Design and Performance of Extraordinary Low-Cost Compact Terahertz Imaging System Based on Electronic Components and Paraffin Wax Optics

Terahertz (THz) imaging is a powerful technique allowing us to explore non-conducting materials or their arrangements such as envelopes, packaging substances, and clothing materials in a nondestructive way. The direct implementation of THz imaging systems relies, on the one hand, on their convenience of use and compactness, minimized optical alignment, and low power consumption; on the other hand, an important issue remains the system cost and its figure of merit with respect to the image quality and recording parameters. In this paper, we report on the design and performance of an extraordinary low-cost THz imaging system relying on a InP Gunn diode emitter, paraffin wax optics, and commercially available GaAs high-electron-mobility transistors (HEMTs) with a gate length of 200 nm as the sensing elements in a room temperature environment. The design and imaging performance of the system at 94 GHz is presented, and the spatial resolution in the range of the illumination wavelength (∼3 mm) and contrast of nearly two orders of magnitude is determined. The operation of two models of the HEMTs of the same nominal 20 GHz cut-off frequency, but placed in different packages and printed circuit board layouts was evaluated at 94 GHz and 0.307 THz. The presence of two competing contributions—self-resistive mixing and radiation coupling through the antenna effects of the printed circuit boards—to the detected signal is revealed by the signal dependence on the gate-to-source voltage, resulting in a cross-sectional responsivity of 27 V/W and noise-equivalent power of 510 pW/Hz at 94 GHz. Further routes in the development of low-cost THz imaging systems in the range of EUR 100 are considered

Do the customers remember?:The fade-out effect from the demand response applied in the district heating system in Denmark

Buildings can deliver short-term thermal energy storage to energy systems. In district heating (DH) systems, it is mainly desk studies and simulations that reveal a large thermal flexibility potential. Knowledge from real-life case studies on how residents participate in demand management campaigns is crucial for the successful utilisation of buildings’ flexibility potential for minimizing bottlenecks in the daily operation of DH systems. In the field study including 72 single-family houses connected to the 3GDH network in southern Denmark, the demand response (DR) strategy “night setback” was applied for two heating periods. The houses were equipped with control and monitoring equipment, which allowed the deactivation of the heating system while monitoring the indoor temperature, so it does not drop below the defined value. The occupants controlled the DR events settings and could at any time stop utilisation of the night setback strategy (implicit participation in the DR). All 72 houses applied the night setback during both heating periods. Yet, the participation time decreased from 89% to 81%. The lowest participation rate was noted for the farm house, 60% and 9% of heating periods 1 and 2, respectively. In around 60% of the DR events, the night setback strategy was activated at 20:00

InGaAs Diodes for Terahertz Sensing—Effect of Molecular Beam Epitaxy Growth Conditions

InGaAs-based bow-tie diodes for the terahertz (THz) range are found to be well suited for development of compact THz imaging systems. To further optimize design for sensitive and broadband THz detection, one of the major challenges remains: to understand the noise origin, influence of growth conditions and role of defects for device operation. We present a detailed study of photoreflectance, low-frequency noise characteristics and THz sensitivity of InGaAs bow-tie diodes. The diodes are fabricated from InGaAs wafers grown by molecular beam epitaxy (MBE) on semi-insulating InP substrate under different technological conditions. Photoreflectance spectra indicated the presence of strong built-in electric fields reaching up to 49 kV/cm. It was demonstrated that the spectral density of voltage fluctuations at room temperature was found to be proportional to 1/f, while at lower temperatures, 77–200 K, Lorentzian-type spectra dominate due to random telegraph signals caused by individual capture defects. Furthermore, varying bias voltage, we considered optimal conditions for device room temperature operation in the THz range with respect to signal-to-noise ratio. The THz detectors grown with beam equivalent pressure In/Ga ratio equal to 2.04 exhibit the minimal level of the low-frequency noise, while InGaAs layers grown with beam equivalent pressure In/Ga ratio equal to 2.06 are found to be well suited for fabrication of room temperature bow-tie THz detectors enabling sensitivity of 13 V/W and noise equivalent power (NEP) of 200 pW/√Hz at 0.6 THz due to strong built-in electric field effects

Titanium-based microbolometers

Terahertz (THz) imaging and spectroscopy set-ups require fine optical alignment or precise control of spatial mode profile. We demonstrate universal, convenient and easy-to-use imaging—resonant and broadband antenna coupled ultrasensitive titanium-based—dedicated to accurately adjust and control spatial mode profiles without additional focusing optical components of weak power THz sources. Versatile operation of the devices is shown using different kinds of THz—electronic multiplier sources, optical THz mixer-based frequency domain and femtosecond optoelectronic THz time-domain spectrometers as well as optically pumped molecular THz laser. Features of the microbolometers within 0.15–0.6 THz range are exposed and discussed, their ability to detect spatial mode profiles beyond the antennas resonances, up to 2.52 THz, are explored. Polarization-sensitive mode control possibilities are examined in details. The suitability of the resonant antenna-coupled microbolometers to resolve low-absorbing objects at 0.3 THz is revealed via direct, dark field and phase contrast imaging techniques as well