Adaptive filtering of harmonic interference when receiving signals with quadrature amplitude modulation.

Quadrature amplitude modulation (QAM) signals are widely used in modern information transmission systems. The quality of the receiver of such signals is significantly reduced if non-fluctuation interference is present in the communication channel. Narrow-band (harmonic) interference with the frequency of the useful signal is especially dangerous. The aim of this work is to develop and study an adaptive algorithm for suppressing such interference when receiving QAM signals. The algorithm is based on a non-recursive digital filter with adjustable weights. It uses known information about the shape of the phase pulse of the signal. The efficiency of the algorithm is investigated by the method of computer simulation. When checking the performance of the algorithm, the spectrum of the signal and noise, the amplitude-frequency characteristic of the adaptive filter and the change in its shape over time were estimated. For 4-QAM and 16-QAM signals, the dependences of the bit error probability on the intensity of harmonic interference and on the signal-to-noise ratio are obtained. It is shown that the adaptive filter effectively suppresses harmonic interference with a relative intensity µ> 0.2 when receiving a 4-QAM signal. The energy advantage is 2 dB or more. When receiving QAM signals with M ≥16, which also have amplitude modulation, the algorithm remains operational, but the efficiency of using this adaptive filter is much lower. The energy advantage does not exceed 0.5 dB.

VDAC—A Primal Perspective

The evolution of the eukaryotic cell from the primal endosymbiotic event involved a complex series of adaptations driven primarily by energy optimization. Transfer of genes from endosymbiont to host and concomitant expansion (by infolding) of the endosymbiont’s chemiosmotic membrane greatly increased output of adenosine triphosphate (ATP) and placed selective pressure on the membrane at the host–endosymbiont interface to sustain the energy advantage. It is hypothesized that critical functions at this interface (metabolite exchange, polypeptide import, barrier integrity to proteins and DNA) were managed by a precursor β-barrel protein (“pβB”) from which the voltage-dependent anion-selective channel (VDAC) descended. VDAC’s role as hub for disparate and increasingly complex processes suggests an adaptability that likely springs from a feature inherited from pβB, retained because of important advantages conferred. It is proposed that this property is the remarkable structural flexibility evidenced in VDAC’s gating mechanism, a possible origin of which is discussed.

Areas of energy advantage for flowsheets of separation modes for mixtures containing components with similar volatilities

Objectives. The conditions for the effective application of the sharp distillation technique (without a component distributed between the distillate and bottom flows) for the separation of quaternary zeotropic mixtures containing components with similar volatilities were determined. The area of energy advantage for the flowsheet based on the preliminary fractionation of the mixture, compared with the flowsheet, the first distillation column of which works based on the indirect separation mode, was identified for an ethyl acetate–benzene–toluene–butyl acetate system. Energy savings of up to 20% were achieved. The direct and indirect distillation modes can become competitive when the point of the original composition is located near single K-surfaces or in a region with a different ratio of distribution coefficients. Sharp distillation is not suitable for the separation of a mixture containing a pair of components exhibiting relative unity volatility with medium boiling points.Methods. The mathematical modeling in the Aspen Plus V.10.0 software package was chosen as the research method. The simulation was based on the Wilson local composition equation. The relative errors in the description of the phase equilibrium did not exceed 3%.Results. The structure of the vapor–liquid equilibrium diagram and diagram of surfaces of the unit component distribution coefficients were studied for the ethyl acetate–benzene–toluenebutyl acetate and acetone–toluene–butyl acetate–o-xylene systems. Flowsheets based on the sharp, indirect (both systems), or direct (second system) distillation modes were proposed. The distillation process was simulated, and the parameters of the column work were determined (the quality of the substances meets the State Standard requirements of the Russian Federation for minimal energy consumption).Conclusions. Recommendations regarding the use of sharp distillation for the separation of quaternary mixtures containing components with similar volatilities were devised.

A reality based cost-benefit analysis of high performance residences: Part II

This research initiative attempts to determine, from real construction cost estimates, the cost challenge and expected payback period associated with building a high-performance residence in Victoria, BC. This was accomplished through: a simulated tendering process with local contractors, an energy analysis of a case-study residence (Part I of this research initiative), and an in-depth study into the variables governing time-to-amortization. The contractors provided quotes for an as-built “above code” residence (ACR), and a “minimum-code” residence (MCR) with the same floor plan (Note: The as-built above-code residence was not built or designed to any specific performance standard; however, it was found in Part I of this research initiative that when compared to the new BC Step code that it performed at a step 3 designation, bordering on step 4 performance). The results of the tendering process were then compared to the as-built construction costs of the residence. When compared to the MCR, it was found that the ACR has a cost challenge of approximately 22.5%, an energy advantage of 22.5 kWh/m2/year, and a payback period of over 79 years when a fuel inflation rate of 2% is considered. However, many of the components in the ACR assemblies were either for aesthetic appeal (metal-roofing), or comfort (floor-cavity insulation), and therefore it was possible to reduce the cost challenge to just 2.1%, while maintaining an energy advantage of 15 kWh/m2/year and step level 3 designation. This was dubbed the hybrid-residence as it employed a combination of above-code and minimum-code construction assemblies. Based on a simple mortgage increase calculation, it was found that the reduction in operational costs produced by the energy-efficiency measures for this residence services 87% of the mortgage increase taken on by the home buyer.

A reality-based energy analysis of high-performance residences: Part I

This research initiative attempts to empirically determine, with reality-based (real instead of modeled) performance data from energy suppliers, the energy advantage associated with building high performance residence in Victoria, BC. In addition, this initiative created a much-needed benchmark for contractors to gain a firm understanding of the construction details required to achieve the various levels of the “Step Code” in the newest edition of the British Columbia Building Code. This was accomplished through a comparative energy analysis between a case-study high-performance “above-code residence” (ACR) to a “minimum code residence” (MCR) with the same floor plan. The ACR was built in 2015 before the step code was introduced, and therefore it was not determined what step level it achieved when it was built. It was not built to any particular performance standard, rather it was built using design details that were calculated to exceed Part 9 performance in effective R-value and airtightness. Upon investigation it was determined that the ACR achieved a performance level of “Step 3” bordering on “Step 4” performance. When compared to the MCR, it was found that the ACR has an energy advantage of 22.5 kWh/m2/year. However, many of the components in the ACR assemblies were either for aesthetic appeal (metal-roofing), or comfort (floor-cavity insulation), and therefore it was possible to remove these components (which is important for Part II of this study: An in-depth cost analysis between the two residences) while maintaining an energy advantage of 15 kWh/m2/year and step level 3 designation. This was dubbed the hybrid-residence as it employed a combination of above-code and minimum-code construction assemblies.

The Heated Condensation Framework. Part II: Climatological Behavior of Convective Initiation and Land–Atmosphere Coupling over the Conterminous United States

This is Part II of a two-part study introducing the heated condensation framework (HCF), which quantifies the potential convective state of the atmosphere in terms of land–atmosphere interactions. Part I introduced the full suite of HCF variables and applied them to case studies with observations and models over a single location in the southern Great Plains. It was shown in Part I that the HCF was capable of identifying locally initiated convection and quantifying energetically favorable pathways for initiation. Here, the HCF is applied to the entire conterminous United States and the climatology of convective initiation (CI) in relation to local land–atmosphere coupling (LoCo) is explored for 34 summers (June–August) using the North American Regional Reanalysis (NARR) and observations. NARR is found to be capable of capturing the convective threshold (buoyant mixing potential temperature θBM) and energy advantage transition (energy advantage potential temperature θadv) for most of the United States. However, there are compensating biases in the components of moisture qmix and temperature q*, resulting in low θBM biases for the wrong reason. The HCF has been used to show that local CI occurred over the Rocky Mountains and the southern Great Plains 35%–65% of the time. Finally, the LoCo process chain has been recast in light of the HCF. Both positive and negative soil moisture–convective feedbacks are possible, with negative feedbacks producing a stronger response in CI likelihood under weak convective inhibition. Positive feedbacks are present but weaker.

Feasibility Study of Heat Pump in Maine Using Attic Heat Source

Heat pumps have been widely studied and used as heating sources for decades in the southern part of the United States. In Maine, however, heat pumps are not popular because of a perception that they are of marginal utility in cold climates. Usage has generally been limited to ground-source units, which are expensive to install. Air-source devices require less up-front investment, and can be used as supplemental heat sources. This study focuses on the feasibility of heat pump usage in Maine by utilizing attic air as the heat source. To this end, a heat pump was installed to heat up a 150 liter water tank. Testing was conducted in fall and winter, and the results demonstrate the energy advantage of using a heat pump.