The energy intensity in Lithuania during 1995–2009: A LMDI approach

The measurement, assessment, and effective mitigation of energy intensity compose a foremost objective of contemporary energy policy. Although the European Union (EU) Member States have been experiencing the convergence in energy efficiency indicators, Lithuania, acceded to the EU in 2004, still remains peculiar with relatively high energy intensity. Our study, therefore, is aimed at analyzing the energy intensity trends in Lithuanian economy as a whole as well as in separate economic sectors. The investigation covers the period of 1995–2009. The Logarithmic Mean Divisia Index was applied for decomposition analysis. Our analysis has shown that energy efficiency falls during economic downturn. In order to facilitate these challenges the Lithuanian Government as well as business should opt for increasing energy efficiency in the most problematic sectors of transport and services. In addition, the analysis of legal acts, namely National Energy Efficiency Programme for 2006–2010 and Energy Efficiency Action plan for 2010–2016, was taken into consideration. Some suggestions, thus, were offered for successful implementation of strategic goals outlined in the aforementioned strategic documents.     

Compact Modules for Wireless Communication Systems in the E-Band (71–76 GHz)

The millimeter-wave spectrum above 70 GHz provides a cost-effective solution to increase the wireless communications data rates by increasing the carrier wave frequencies. We report on the development of two key components of a wireless transmission system, a high-speed photodiode (HS-PD) and a Schottky Barrier Diode (SBD). Both components operate uncooled, a key issue in the development of compact modules. On the transmitter side, an improved design of the HS-PD allows it to deliver an output RF power exceeding 0 dBm (1 mW). On the receiver side, we present the design process and achieved results on the development of a compact direct envelope detection receiver based on a quasi-optical SDB module. Different resonant (meander dipole) and broadband (Log-Spiral and Log-Periodic) planar antenna solutions are designed, matching the antenna and Schottky diode impedances at high frequency. Impedance matching at baseband is also provided by means of an impedance transition to a 50 Ohm output. From this comparison, we demonstrate the excellent performance of the broadband antennas over the entire E-band by setting up a short-range wireless link transmitting a 1 Gbps data signal.     

Electron ensemble coherence and terahertz radiation amplification in a cascade superlattice structure

We report on an ensemble Monte Carlo study of the electron dynamics in a biased GaAs/AlGaAs cascade superlattice structure with domains of a strong electric field. We simulate the electron transport in a single superlattice, serving as an active region of the structure, and verify Kroemer's criterion which specifies over which distance in a superlattice a stable domain forms. We show that at room temperature in a superlattice with electrons subject to scattering at optical and acoustic phonons, the deviation of the superlattice length critical for domain development from that which is determined by Esaki–Tsu formula, varies from 10% to 300%. In a superlattice with the length larger than the critical one due to the electric field non-homogeneity, an electron ensemble becomes incoherent and its interaction with a terahertz field causes only the damping of the latter.     

Fast High-Voltage Light Triggered Superconducting Opening Switch

The dynamics of light induced switching from the super-conducting or mixed state to the normal state were investigated in thin Y-Ba-Cu-0 films biased by high-current nanosecond pulses. It was demonstrated that the subnanosecond duration voltage transients with amplitudes of up to several hundred volts which are generated by the light triggered super-conducting opening switch are the result of film heating by light pulses and the bias current.     

Camera for High-Speed THz Imaging

Journal of Infrared, Millimeter, and Terahertz Waves - We present a 24 × 24 pixel camera capable of high-speed THz imaging in power-detection mode. Each pixel of the sensor array consists of a...     

Imaging and Spectroscopic Sensing with Low-Repetition-Rate Terahertz Pulses and GaN TeraFET Detectors

Aiming for non-destructive testing and security applications, we investigate transmission-mode imaging and spectroscopic sensing using terahertz (THz) pulses from a commercial optical parametric oscillator (OPO) in combination with THz detectors based on antenna-coupled field-effect transistors (TeraFETs). The Q-switched OPO generates quasi-continuous-wave THz pulses with a peak power of up to 1 W at a repetition rate between 12 and 90 Hz. The pulses are frequency-tunable between 0.7 and 2.6 THz with a typical linewidth of 50 GHz. We explore detection with fast GaN/AlGaN TeraFETs which hold the potential for multi-pixel and homodyne detection.     

Terahertz imaging with GaAS field-effect transistors

Imaging at 0.6 THz is tested with a commercial GaAs high-electron-mobility transistor (HEMT) operated at room temperature. The results allow the assessment of the potential of future antenna-fitted HEMT arrays for real-time imaging.     

Prioritizing sustainable electricity production technologies: MCDM approach

Economic, technological, social, and political developments stressed the need for shifts in energy-mix. Therefore it is important to provide a rationale for sustainable decision making in energy policy. The aim of this paper is to develop the multi-criteria decision support framework for choosing the most sustainable electricity production technologies. Given selection of sustainable energy sources involves many conflicting criteria, multi-criteria decision methods MULTIMOORA and TOPSIS were employed for the analysis. The indicator system covering different approaches of sustainability was established. The analysis proved that the future energy policy should be oriented towards the sustainable energy technologies, namely water and solar thermal ones. It is the proposed multi-criteria assessment framework that can constitute a basis for further sub-regional optimization of sustainable energy policy.     

Terahertz Imaging Detectors in CMOS Technology

Square-law power detection circuits with on-chip antennas and amplifiers are presented for the detection of 0.65-THz radiation in a low-cost 0.25-μm CMOS technology. The circuit architecture combines metal-insulator-metal (MIM) coupling capacitors with NMOS transistors to facilitate self-mixing in a resistive mixer. A low-frequency (quasi-static) and a high-frequency (non-quasi-static) analysis of the broad-band circuit is presented. Current and voltage readout techniques of non-amplified detectors are compared, and exhibit a measured responsivity of 5.3 mA/W and 150 V/W respectively. A monolithic integrated 3×5 pixel focal-plane array has been used for single-pixel and multi-pixel imaging of concealed objects at 0.65 THz.