Offset Energy Research Articles

Microwave-Assisted Synthesis of CdS-MOF MIL-101 (Fe) Composite: Characterization and Photocatalytic Performance.

The present study outlines the synthesis of cadmium sulfide-metal-organic framework (CdS-MOF) MIL-101 (Fe) heterojunctions achieved via fast microwave-assisted reactions. Thus, different CdS-MOF MIL-101 (Fe) ratios were prepared to study their effectiveness as photocatalysts. These compounds were employed in the photocatalytic degradation of methylene blue (MB) under UV and visible irradiation. Structural, morphological, textural, compositional, and optical properties of the synthesized compounds determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were utilized to characterize the structural, morphological, textural, compositional, and optical properties. Electrochemical impedance spectroscopy (EIS) was also employed to determine photovoltage and photocurrent densities. The resulting valence band offset (Vfb) and band gap energy values were utilized to construct an energy band scheme. Our research revealed that the CdS-MOF MIL-101 (Fe) heterojunction enhances the efficiency of electron-hole pair separation, thereby mitigating charge carrier recombination effects. Moreover, the type I electronic band structure established an efficient reaction mechanism, effectively suppressing the recombination of photogenerated electron-hole pairs. The photocatalytic system demonstrated exceptional behavior, achieving complete MB removal within 30 min of reaction time and exhibiting outstanding stability and reusability after four reaction cycles. These findings highlight the potential of the synthesized compounds in the field of wastewater treatment for organic pollutants, offering a promising alternative to current environmental issues.

The Impact of Multifunctional Ambipolar Polymer Integration on the Performance and Stability of Perovskite Solar Cells

AbstractEffective passivation of grain boundaries in perovskite solar cells is essential for achieving high device performance and stability. However, traditional polymer‐based passivation strategies can introduce challenges, including increased series resistance, disruption of charge transport, and insufficient passivation coverage. In this study, a novel approach is proposed that integrates a multifunctional ambipolar polymer into perovskite solar cells to address these issues. The ambipolar polymer is successfully incorporated into both the perovskite film and the hole transport layer (HTL), enabling comprehensive restoration of defect sites within the perovskite active layer. Moreover, this approach yields additional advantages for perovskite devices, such as enabling bidirectional charge transport, limiting pinhole formation at the HTL, reducing lithium‐ion migration from the HTL to the perovskite, and minimizing both the band offset and surface energy difference between the perovskite film and HTL interface. With these benefits, the ambipolar polymer integrated device achieves a power conversion efficiency (PCE) of 24.0%. Remarkably, it also exhibits enhanced long‐term stability, preserving 92% of its initial PCE after 2000 h under ambient conditions, and 80% of its initial PCE after 432 h under harsh conditions (at 85 °C and 85 ± 5% RH).

Performance Assessment of Ground Source Heat Pumps to Offset Domestic Energy Consumption in Pakistan

Abstract: This paper presents an experimental based performance evaluation of ground source heat pumps (GSHP) to offset domestic energy consumption in Pakistan. Global population growth and rising energy consumption drove up demand for fossil fuels, adding to pollution and hastening the effects of climate change. A clean, renewable, durable, and cost-effective technology is GSHPs, which could help ease the burden of energy-intensive industries like residential cooling and heating. But due to the lack of performance characteristics of GSHP, resulting in less people opting for its installation and usage in homes. The performance assessment of GSHP system is carried out to provide financial sustainability of using this technology for heating and cooling in homes. It will also enable the readers to know the price range of this system and hence, better prepare them to take more informed decisions in the use of energy conservation and the quest for alternative/renewable energy means. The results show that by installing GSHP system, reduced excavation/backfilling, materials and other component ((like pump, radiator, water tank) costs that contributed 50%, 20% and 30% of the total costs of the system respectively. It is also noted that that GSHP system (1500ft of pipe length, placed at shallowest depth of 15ft) took 2.16 years while the system (placed at 15ft depth and having heat exchanger length of 1000ft) took 0.64 years to return its cost. If the GSHP system is insulated efficiently it can produce 3 to 4.5 time’s electrical energy that can serve for heating multiple homes. Based on these results, it can be concluded that GSHP system can be considered a viable solution to offset domestic energy consumption in Pakistan.

Offering and bidding for a wind producer paired with battery and CAES units considering battery degradation

This paper presents a stochastic framework for offering and bidding strategies of a hybrid power generation system (HPGS) with a wind farm and two types of energy storage facilities, i.e., compressed air energy storage (CAES) and battery energy storage (BES) systems. The model considers the participation of the HPGS in consecutive electricity markets, i.e., day-ahead (DA) and intraday markets. To better address the proposed trading strategy problem, the BES degradation cost is also incorporated into the model. Furthermore, a mechanism based on energy procurement from demand response resources (DRRs) in the intraday demand response exchange (IDREX) market for the HPGS is also established to offset unexpected energy imbalances effectively. The suggested offering and bidding strategy is formulated as a three-stage stochastic programming problem incorporating a risk-alleviating index, namely, the conditional value-at-risk (CVaR). Results from several simulations indicate considerable profit gain and risk reduction achieved by the suggested offering and bidding framework.

New techniques for the energy saving of sustainable buildings by using phase change materials

Efficiency and energy system improvement are among the main important modern studies centered the energy consumption reduction and thermal performance enhancement of buildings. The main objective of this study is saving the energy of sustainable buildings by using paraffin wax as phase change materials (PCMs) and pumice fine aggregates (PUs) with concrete hollow blocks (CHBs) by using the cement mortars into the walls and ceilings (CILs). The effects investigated on temperature reduction and their role is improving thermal performance, thermal comfort, and electrical consumption energy savings of buildings. Eight concrete hollow blocks CHBs specimens were prepared using the cement mortars. The first group consists of four specimens included CHBs (Standard; without mortar) and the other three mixtures with different percentages of PCMs (0%, 50%, and 75%) by volume of sand. The second group was prepared using PUs aggregate that consists of three CHBs specimens with different percentages of PCMs (0%, 50%, and 75%) by volume of PUs, that prepared to investigate the effects of PUs aggregate and PCMs replacement on the thermal properties. The eighth CHBs specimen was filled with pure PCMs. The thermal properties of the prepared specimens were performed by Differential Scanning Calorimetry (DSC), thermal Conductivity (K- Value), and heat transfer evolution (HTE) analysis technique. Four rooms were built with a 6 cm ceiling thickness and CHBs walls, to study the effect of PCMs and PUs on the thermal properties. The temperature evolution in the rooms and the offset peak hours, cooling load, and energy cost savings were investigated. Results indicate improving the thermal properties of the tested specimens. The room results show a decrease in the indoor temperature of the room with 5.75 °C. The cooling load reduction was 26%, corresponding to an electricity consumption savings of approximately $2.76/Day m3. Based on all results, thermal performance tests showed that the modal room with the PCMs + PUs can be improved thermal comfort keeping the indoor temperature at the comfortable range for a large time and reduced the electrical consumption energy of buildings.

Pulse shaping methods for inter carrier interference reduction in OFDM system

The weakness of the orthogonal freuency division multiplexing (OFDM) system is susceptible to the existence of carrier frequency offset (CFO) which causes the emergence of inter carrier interference (ICI) which causes a degradation of performance OFDM systems. This study aims to apply the suggested rectangular (REC) pulse and improved sinc-power (ISP) pulse shaping methods on OFDM system and determines ICI reduction with the effects of CFO over flat fading Rayleigh channels. The performance of each pulse shaping method is evaluated and compared based on parameter ICI power vs. normalized frequency offset, signal to interference ratio (SIR) vs. normalized frequency offset and bit error rate (BER) vs. energy bit per noise (Eb/No). The simulation result in terms of BER vs. Eb/No indicated that REC and ISP pulse shaping has better performance dealing with ICI reduction compared to OFDM system no applied pulse shaping. In addition, the ISP is able to mitigate ICI better than REC.

Performance and improvement of cleanroom environment control system related to cold-heat offset in clean semiconductor fabs

Clean room is a key technology to guarantee the normal operation in semiconductor manufacturing industry. On-site measurement of indoor environment and performances of the air conditioning systems in four clean semiconductor fabs have been conducted in summer in this study. It’s indicated that indoor environment of these four fabs all meet the requirement and a satisfied control accuracy is achieved. The main energy-consuming facilities in the air conditioning system arises from the fan of air handling processors and chillers, which consumes about 80%–90% of the total. Reheating in make-up air handing process (MAU) occurs in the current system, resulting in cold-heat offset and extra energy loss. System schematic avoiding reheating based on the measured results is proposed. The proposed system where only part of indoor return air is cooled by the dry cooling coil (DCC) and achieves secondary return air could avoid the cold-heat offset. At full load condition, cooling supplies for DCC (QDCC) in the proposed system is about 40%–52% lower than that in the current system of these four fabs. No reheating exists in the proposed system, and QRH is saved 151–236 W/m2. The research helps to reveal the operating performance and propose appropriate improving approaches for these circumstances.

Dynamic reconfiguration of distribution network with new energy generation considering economic and reliability

The penetration rate of new energy power generation in the distribution network has gradually increased, and the traditional static reconfiguration for a certain time section will be difficult to meet the actual operation requirements of the distribution network. A dynamic reconfiguration model of the distribution network with network loss, voltage offset, and new energy abandonment rate as the optimization goals was established. An adaptive genetic algorithm was used to solve the dynamic reconfiguration optimization of the distribution network. By simplifying the traditional network, a large number of infeasible solutions generated during the encoding process are reduced, and the optimization ability of the algorithm is improved. Based on the IEEE33 node system, four different scenarios were set up for simulation analysis. The results show that the reconfiguration can significantly reduce the network loss and voltage offset of the system, and also significantly improve the utilization efficiency of new energy and effectively improve the operation level of the distribution network. The feasibility and correctness of this method were verified.

Fabrication of nano-TiC reinforced high Nb-TiAl nanocomposites by electron beam melting

Electron beam melting (EBM) has been successfully applied to fabricate TiC reinforced high Nb-containing TiAl matrix (TiC/Nb-TiAl) nanocomposite. The optimised combination of focus offset and line energy in the melt stage have been developed to achieve a uniformly distributed nano-TiC particles within the TiAl matrix. The EBM TiC/Nb-TiAl nanocomposite has a microhardness of 393 ± 31 HV0.2, that is 24% higher than that for high Nb-TiAl alloy alone. It is interesting to note that the uniformly distributed nano-TiC particles lead to the formation of equiaxed α2-phase in TiAl matrix, instead of those commonly observed γ-phase in previous EBM γ-TiAl work.

Mechanical degradation model of porous magnesium scaffolds under dynamic immersion

A new generation of bone scaffolds incorporates features like biodegradability and biocompatibility. A combination of these attributes will result in having a temporary bone scaffold for tissue regeneration that mimics the natural cancellous bone. Under normal conditions, scaffolds will be gradually eroded. This surface erosion occurs due to the immersion and the movement of bone marrow. Surface erosion on bone scaffolds leads to changes of the morphology. The mechanical response of the scaffolds due to the surface erosion is not fully understood. The aim of this study is to assess the influence of the dynamic immersion condition on the degradation behaviour and mechanical properties of porous magnesium. In the present work, load-bearing biomaterial scaffolds made of pure magnesium are immersed in simulated body fluids (SBF) with a certain flow rate. Samples with different porosities are subjected to tomography and are used to develop virtual 3D models. By means of numerical simulations, the mechanical properties, for instance, elastic modulus, plateau stress, 0.2% offset yield stress and energy absorption of these degraded samples are collected. The findings are then validated with the values obtained from the experimental tests. Finite element method enables the study on the failure mechanism within the biomaterial scaffolds. The knowledge of how weak walls or thin struts collapsed under compressive loading is essential for future biomaterial scaffolds development. Results from the experimental tests are found in sound good agreement with the numerical simulations.

Detection of cyclotron resonance using photo-induced thermionic emission at graphene/MoS2 van der Waals interface

We demonstrate the detection of cyclotron resonance in graphene by a photo-induced thermionic emission mechanism at the graphene/MoS2 van der Waals (vdW) Schottky junction. At cyclotron resonance in Landau-quantized graphene, the infrared light is absorbed, and an electron–hole pair is generated. When the energy of a photoexcited electron exceeds the band offset energy at the graphene/MoS2 interface, the electron transfer occurs from graphene to the conduction band of MoS2, and the hole remains in graphene. This creates an electron–hole separation at the graphene/MoS2 interface at cyclotron resonance, and a photovoltage is generated. The proposed method is an infrared photodetection technique through out-of-plane transport at the vdW junction, which is distinct from the previously reported methods that use in-plane transport in graphene for electronic detection of the cyclotron resonance. Despite the simple structure of our device with a single-vdW junction, our method exhibits a very high sensitivity of ∼106 V/W, which shows an improvement of three orders of magnitude over the previously reported values. Therefore, the proposed method displays a high potential for cyclotron resonance-based infrared photodetector applications.

Dopant‐Dependent Increase in Seebeck Coefficient and Electrical Conductivity in Blended Polymers with Offset Carrier Energies

AbstractThe strong and counterproductive interrelationship of thermoelectric parameters remains a bottleneck to improving thermoelectric performance, especially in polymer‐based materials. In this paper, a compositional range is investigated over which there is decoupling of the electrical conductivity and Seebeck coefficient, achieving increases in at least one of these two parameters while the other is maintained or slightly increased as well. This is done using an alkylthio‐substituted polythiophene (PQTS12) as additive in poly(bisdodecylquaterthiophene) (PQT12) with tetrafluorotetracyanoquinodimethane (F4TCNQ) and nitrosyl tetrafluoroborate (NOBF4) as dopants. The power factor increases two orders of magnitude with the PQTS12 additive at constant doping level. Using a second pair of polymers, poly(2,5‐bis(3‐dodecylthiophen‐2‐yl)thieno[3,2‐b]thiophene (PBTTTC12) and poly(2,5‐bis(3‐dodecylthiothiophen‐2‐yl)thieno[3,2‐b]thiophene, (PBTTTSC12), with higher mobilities, decoupling of the Seebeck coefficient and electrical conductivity is also observed and higher power factor is achieved. Distinguished from recently reported works, these two sets of polymers possess very closely offset carrier energy levels (0.05–0.07 eV), and the microstructure, assessed using grazing incidence X‐ray scattering, and mobility evaluated in field‐effect transistors, are not adversely affected by the blending. Experiments, calculations, and simulations are consistent with the idea that blending and doping polymers with closely spaced energy levels and compatible morphologies to promote carrier mobility favors increased power factors.

Same day cerebral perfusion and dopamine transporter imaging for differential diagnosis of cerebral impairment

When cognitive impairment is first evident it can be difficult to distinguish between different conditions such as idiopathic Parkinson's disease and Lewy body dementia. Imaging both cerebral perfusion and dopamine transporter function has been shown to provide accurate differentiation between the most common conditions. At present cerebral perfusion and dopamine transporter imaging is conducted on separate days. Carrying out both scans on the same day has the potential to benefit the patient through the social convenience of one visit to hospital and the earlier availability of results.This work considered whether it was possible to obtain diagnostic quality images from Ioflupane (123I) single positron emission tomography (SPECT) acquired at the same time as or four hours after a Exametazime (99mTc) SPECT on the same day. Possible changes to the Ioflupane (123I) SPECT acquisition and processing protocols such as a new energy window and use of a resolution recovery algorithm were explored using phantom studies.Initial phantom results show that when a four hour delay between acquisitions is used comparable contrast to noise ratios can be achieved (4.23 vs. 4.63) with an insignificant loss in resolution (11.51 mm vs. 11.35 mm full width at half maximum (FWHM)). An offset energy window (159 keV −5.5% & +15.5%) was found to provide the highest contrast to noise ratio. This work provides a proof of concept for same day imaging.

The influence of grain boundary interface traps on electrical characteristics of top select gate transistor in 3D NAND flash memory

The electrical characteristics of top select gate transistor (TSG) has been investigated in vertical channel three dimensional NAND flash memory. TSG shows wider initial Vth distribution as compared with memory cells, and even worse after erase. By experimental analysis and TCAD simulation, a physical model based on grain boundary (GB) interface traps is proposed to explain the mechanism. Grain boundary traps in offset region between bit line contact and TSG can induce a higher local potential barrier in channel, which results in higher TSG initial Vth. Besides, random GB position within offset region, leads to worse variation of TSG initial Vth. Furthermore, the local potential barrier in offset region of TSG cannot be reduced by erase operation, leading to worse Vth distribution after erase. According to proposed model, two methods with optimization of offset doping energy and poly-Si GB trap passivation condition are proposed to achieve tight distribution and improved erase uniformity.

Bimodal velocity distributions in the photodesorption of CO from Si(1 0 0) suggest V-to-T energy transfer

The photodesorption of CO from Si(100) has been studied using 355 and 266 nm light obtaining time-of-flight spectra detailing the translation energy released. The spectra clearly exhibit two non-thermal desorption channels, of which one is characterized by an offset energy the size of which is remarkably close to the vibrational quantum of CO. Detailed studies of the spectra as function of coverage and laser fluence used prove that both desorption channels originate from a single adsorbed species. It is suggested that the energy offset is due to vibrational to translational energy transfer along the reaction pathway of the desorbing molecule.

Influence of various parameters and phenomena on the absorption edge of InAs/GaSb superlattices

In the work we have considered the influence of various parameters and phenomena on the absorption edge of InAs/GaSb superlattices. Calculations have been performed with the use of the 8-band k⋅p method. Results of the analysis have allowed us to form an opinion how big is the impact of temperature, band offset energy, strain and different types of interfaces on the absorption edge of the investigated structures. Such comparison hasn't been done, yet, especially since our outcomes relate not only to the selected, individual superlattices, but present the issue more comprehensively, regarding two series of periodic structures, derived from the (InAs)8ML/(GaSb)8ML one. Conclusions, which come from this work are useful particularly in terms of difficulties in adopting proper values of the material parameters for the numerical model of InAs/GaSb superlattice. Results presented in this article will be helpful while designing the more sophisticated periodic structures based on InAs/GaSb material system.

Reconciling energy efficiency and energy intensity metrics: an integrated decomposition analysis

We develop and illustrate a method for reconciling index decomposition analysis of energy intensity with physically based, sector-specific energy efficiency indicators. Decomposition analysis of individual sector intensity contributions to total energy intensity is nested within the higher-order decomposition analysis of E/GDP such that the contribution of energy efficiency gains to changes in total energy intensity can be determined. Energy, economic and physical activity data for Canada for the period 1995–2010 are used to illustrate the method. Intrasector structural factors were found to be both positive and negative and to be significant contributors to energy intensities in both the business and household sectors. In aggregate, intrasectoral structural change offset energy efficiency gains and put upward pressure on (E/GDP) between 1995 and 2010 but was three times smaller than the offsetting decline in E/GDP due to intersectoral structural change. The method can be used for assessing the contribution of energy efficiency to sector energy intensities; for placing energy efficiency policies in the larger context of the other factors that determine an economy’s energy intensity and greenhouse gas emissions; for identifying non-efficiency policy targets for improving energy productivity; and for increasing the sophistication of forecasting and scenario analysis of future levels and patterns of fuel and electricity consumption and related greenhouse gas emissions.

Waste management in the Irkutsk region, Siberia, Russia: An environmental assessment of alternative development scenarios

The current waste management system, handling around 500,000 t of household, commercial, and institutional waste annually in the Irkutsk region, Siberia, is based on landfilling in an old landfill with no controls of leachate and gas. Life-cycle assessment modelling of the current system shows that it is a major load on the environment, while the simulation of seven alternative systems results in large savings in many impact categories. With respect to climate change, it is estimated that a saving of about 1200 kg CO2 equivalents is possible per year, per inhabitant, which is a significant reduction in greenhouse gas emissions. The best alternatives involve efficient energy recovery from waste and recycling by source separation for commercial and institutional waste, the major waste type in the Irkutsk region. Recycling of household waste seems less attractive, and it is therefore recommended only to consider this option after experience has been gained with the commercial and institutional waste. Sensitivity analysis shows that recovery of energy - in particular electricity, heat, and steam - from waste is crucial to the environmental performance of the waste management system. This relates to the efficiencies of energy recovery as well as what the recovered energy substitutes, that is, the 'dirtier' the off-set energy, the higher the environmental savings for the waste management system. Since recovered energy may be utilised by only a few energy grids or industrial users, it is recommended to perform additional local assessments of the integration of the waste energy into existing systems and facilities.

The mechanical properties of expanded perlite-aluminium syntactic foam at elevated temperatures

Expanded perlite/A356 aluminium syntactic foams (P-MSF) were produced via a counter-gravity infiltration process. The quasi-static compressive properties of these foams were investigated at 25, 125, 250, 375, and 500 °C and compared with those of the matrix material, tested at the same conditions. Young's modulus, offset yield stress, plateau stress and energy absorption was evaluated for all samples. The improved ductility of the foams at higher temperatures results in more uniform deformation and smoother stress-strain curves. At the same time, the mechanical strength and the energy absorption of the foams and the matrix material decrease. The results indicate that the high temperature mechanical properties of the foams are controlled by two counter-acting mechanisms, i.e. the softening of the matrix material and the improved ductility of the foam.

Enhancing the performance of non-fullerene solar cells with polymer acceptors containing large-sized aromatic units

In this work, we develop four diketopyrrolopyrrole-based polymer acceptors for application in polymer-polymer solar cells. The polymer acceptors contain different-sized aromatic units, from small thiophene to benzodithiophene and large alkylthio-benzodithiophene units. Although the polymer acceptor with large-sized groups shows small LUMO offset and low energy loss when blended with the donor polymer PTB7-Th, the corresponding solar cells can achieve a high power conversion efficiency (PCE) of 3.1% due to high photocurrent. In contrast, the polymer acceptor with small thiophene units only provides a low PCE of 0.14% in solar cells. These results indicate that polymer acceptors with large-sized aromatic units can be potentially used into high performance non-fullerene solar cells.