Climate change and energy policy in Eastern Europe: Two scenarios for the future

The citizens of Poland, Eastern Germany, Czechoslovakia, Hungary, and Romania inhabit perhaps the most polluted environments in the world, largely because of their countries' inefficient use of energy. Energy use is two to three times greater per unit of economic output than in Western Europe. Energy inefficiency also constrains economic growth by diverting capital to unproductive use. As much as 40% of all industrial investment in Poland was consumed in energy production.The emerging democracies of Eastern Europe have embarked on reforms to make their economies more efficient. We assess their potential for energy efficiency and apply end-use analysis in an energy end-use economic model to evaluate future energy use in the region. We assume that Eastern Europe will approach current Western living standards over the next three decades and that this will in turn increase energy consumption. We have found, nevertheless, that Eastern European nations could hold energy demand virtually constant through structural reform and technical energy-efficiency improvement. The six countries in the region could save as much as 3.5 exajoules per year, with savings yielding an economic benefit of $300 million annually.Capturing the energy-efficiency potential in Eastern Europe would require a combination of market forces and policy initiatives. Such optimistic prediction, however, should not be taken at face value. Financial and technical constraints will impede some of the potential gains in energy efficiency in Eastern Europe. Overcoming them will require national leadership and decisive international cooperation.     

Dynamical energy limits in traditional and work-driven operations II.: Systems with heat and mass transfer

This is the second part of the work that analyses dynamical energy limits for diverse operations with finite rates important in engineering. Our position is that a dynamic limit of a sufficiently high hierarchy may be helpful in modelling and design of a prescribed operation. In particular, we treat active systems with coupled heat and mass transfer important in separation and biological systems. The operations considered occur in separation units, heat and mass exchangers, energy converters and chemical reactors. The energy limits are expressed in terms of classical exergy and a residual minimum of entropy generated in equipment of a fixed dimension. To ensure physical limits we treat sequential work-driven operations, in particular those of dissolving or evaporation which run jointly with thermal machines (e.g. heat pumps). We also compare structures of optimization criteria describing these limits (in particular “endoreversible limits”) in traditional and work-driven operations. Through quantitative analyses we extend to the realm of mass transfer operations the method initiated in Part I that applies “Carnot variables” as suitable controls. Functions of extremum work, which apply a residual minimum entropy production, are found in terms of initial and final states, duration and (in discrete processes) number of stages. Mathematical analogies between entropy production expressions in traditional and work-driven operations are helpful to formulate optimization criteria in both cases.     

Energy Deposition in a Model of Man: Frequency Effects

A computer-controlled scanning system and implantable, nonperturbing electric field probes were used to measure spatial distributions of the electric field in a full scale homogeneous model of a human body. The measurements were performed at three frequencies (160, 350, and 915 MHz) in the far-field and in the near-field of resonant dipoles. The specific absorption rate (SAR) distributions and the averages for body parts and the whole body are analyzed as functions of frequency. In the far-field, the SAR decreases exponentially in the direction of wave propagation in the torso at all frequencies, and large gradients of the SAR are observed along the body main axis, particularly for the E polarization. At 160 and 350 MHz high local SAR's are produced in the neck. It appears that for plane wave exposures the ratio of the peak SAR to the whole-body average SAR does not exceed 20. In the near-field, large SAR gradients are also produced, and the ratios of the peak spatial SAR to the whole-body average SAR vary from about 30 to 250 depending on the frequency and polarization. It is suggested that for near-field exposures the whole-body average SAR is not a proper dosimetric measure, and the SAR averaged over any 0.1 of the tissue volume is recommended instead.     

Fluid flow identification on base of the pressure difference measured on the secant of a pipe elbow

The paper presents a new method for indirect flow rate measurement in elbow flow meters. The idea of the method consists in selecting such a Reynolds number value, assumed as a coefficient in fluid flow equations, which fulfils with set accuracy the condition of equality between the measured and the computed pressure difference at the end points of the secant of the elbow arch. The calculus takes into account also the accurate flow geometry, the values of coefficients which describe the thermo-physical properties of the fluid at the measurement temperature, and proper equations of the turbulence model. A special test stand was arranged in order to implement the proposed method in practice. The numerical computations were carried out using the software package FLUENT 6.1. The results of calculations were compared with the corresponding results of measurements achieved on the stand, as well as ones found in the bibliography [?, ?]. A comparison of the outcome of calculations with experimental readings shows a high grade of consistence.     

Manufacturing and physico-mechanical characterization of carbon nanohorns/polyacrylonitrile nanocomposites

The use of carbon nanohorns (SWCNHs) as a modifying filler in a polyacrylonitrile (PAN) matrix is studied with the goal of elaborating nanocomposites. The study deals with assessment of the dispersity of SWCNHs in a PAN polymer suspension. The SWCNHs were introduced into the PAN-based suspension using different methods, including mechanical stirring, ultrasonification and the combination of ultrasonification with addition of a surfactant. Agglomeration and dispersion processes of SWCNH in the polymer suspensions were studied using DLS technique and turbidimetry. The resulting properties of nanocomposite foils after solidification in water ambient were verified in various tests. The mechanical tensile properties (tensile strength, modulus and strain to fracture) of the nanocomposites before and after the dispersion process were compared. The nanocomposites obtained under optimally prepared suspension perform the highest strain to fracture in tensile test. Electrical resistivity and thermal conductivity of nanocomposites samples after appropriate dispersion of SWCNHs in the PAN suspension were also determined. The presence of SWCNH in the PAN suspension affects the structure of nanocomposites after solidification through changing structural ordering of the polymer. The study revealed that the polymeric suspensions prepared in optimum processing conditions contain the carbon aggregates the size of which correspond almost to the mean size of a dahlia flower-like structured particle, i.e., 50–250 nm and it was not possible to separate such particles into a single form of carbon nanohorn by the techniques used.     

Photolithographic patterning of organic photodetectors with a non-fluorinated photoresist system

We report on the fabrication of organic photodetectors (OPD) based on isolated islands of P3HT:PCBM. Pattern transfer to the active material was done with photolithography based on non-fluorinated solvents and the excessive organic semiconductor was removed with oxygen plasma reactive ion etching. The photoresist system used was found to be benign to the P3HT:PCBM layer as confirmed by absorption, thickness and roughness measurements. Current–voltage characteristics and external quantum efficiency (EQE) remained unchanged after the patterning process. It was demonstrated that it is possible to photolithographically pattern isolated islands with 200 μm edge length with the same dark current density (<10⁻⁵ A/cm² at −2 V bias voltage) and photocurrent density (>5 × 10⁻³ A/cm² at −2 V). Furthermore, concerning the solar cell performance, the patterned, small-area devices showed power conversion efficiency of 2.1% and fill-factor of 60%. Dark current was observed to depend on the size of the remaining semiconductor island, which was demonstrated on OPDs with diameter of 50 μm. The presented results show the feasibility of fabrication of isolated devices based on organic semiconductors patterned with non-fluorinated photolithography.     

RF Energy Deposition in a Heterogeneous Model of Man: Near-Field Exposures

The electric field strength was measured in a full-scale heterogeneous model of man exposed in the near field of resonant dipoles. The model was comprised of skull, spinal cord, rib cage, all other major bones, brain, lung, and muscle tissue. Electrical properties of these simulated tissues were the same as respective live tissue properties at test frequencies of 160, 350, and 915 MHz. The rates of energy absorption were calculated on the basis of the measured field strengths and tissue conductivities. Patterns of the energy deposition are compared for two orientations of the antennas with respect to the body. Also the results for the heterogeneous model are compared to data for homogeneous model having average tissue electrical properties.