Collection Efficiency Research Articles

High-Sensitivity and In Situ Multi-Component Detection of Gases Based on Multiple-Reflection-Cavity-Enhanced Raman Spectroscopy.

Raman spectroscopy with the advantages of the in situ and simultaneous detection of multi-components has been widely used in the identification and quantitative detection of gas. As a type of scattering spectroscopy, the detection sensitivity of Raman spectroscopy is relatively lower, mainly due to the low signal collection efficiency. This paper presents the design and assembly of a multi-channel cavity-enhanced Raman spectroscopy system, optimizing the structure of the sample pool to reduce the loss of the laser and increase the excitation intensity of the Raman signals. Moreover, three channels are used to collect Raman signals to increase the signal collection efficiency for improving the detection sensitivity. The results showed that the limits of detection for the CH4, H2, CO2, O2, and N2 gases were calculated to be 3.1, 34.9, 17.9, 27, and 35.2 ppm, respectively. The established calibration curves showed that the correlation coefficients were all greater than 0.999, indicating an excellent linear correlation and high level of reliability. Meanwhile, under long-time integration detection, the Raman signals of CH4, H2, and CO2 could be clearly distinguished at the concentrations of 10, 10, and 50 ppm, respectively. The results indicated that the designed Raman system possesses broad application prospects in complex field environments.

Controlling the spontaneous emission of the telecom O-band centers in Silicon-on-Insulator with coherent dipole-quadrupole interactions on a silicon pillar lattice

The G-center in silicon-on-insulator (SOI) has emerged as a relevant single photon source due to the zero-phonon line at 1278 nm, matching the O-band of optical telecommunication wavelengths. Due to the weak emission of the G-center from planar SOI, it is necessary to enhance its emission, in terms of collection efficiency and fluorescence enhancement, to further study its optical properties for application in quantum technologies. Here we design a fabrication-ready SOI Mie-resonator made of a lattice of silicon nanopillars on silica to achieve the spontaneous emission enhancement of single G-centers. Using Si nanopillars lattice on silica with period and dimensions optimized, owing to the coherent superposition of the electric dipolar and magnetic quadrupolar electromagnetic Mie-scattering moments of the individual pillars to the periodic lattice, we show the G-center emission/decay rate enhancement averaged over it's possible dipole orientations is about 13 times compared to bulk. This corresponds to a fluorescence enhancement of about 125 times compared to bulk and about 5-6 times compared to an optimized single pillar with photon collection with a confocal objective. These results provide a fabrication pathway for out-of-plane single photon collection from the SOI G-center or other telecom O-band single-photon sources for their potential deployment in CMOS-compatible quantum optical technologies.

Realizing enhanced photoresponse for self-powered broadband photodetector with asymmetric contacts based MoTe2/WSe2 van der Waals heterostructure

Self-powered photodetectors constructed by two-dimensional (2D) materials are significant in advanced science and technology with the growing focus on green and energy-efficient solutions. The built-in electric field in photodetector drives efficient separation and transfer of photogenerated electron–hole pairs. However, traditional metal-2D material-metal structures have more interface defects and larger Schottky barrier to hinder carrier transport. In this work, an asymmetric electrode material structure is constructed by adding graphene to provide a more efficient transport channel for photogenerated carriers. Graphene electrodes can play a variety of roles in efficient separation and collection of photogenerated carriers, reducing the barrier and improving the contact quality. Compared with the device using symmetric gold electrodes, the device prepared with asymmetric contacts show optimized performance. The MoTe2/WSe2 heterostructure exhibits brilliant self-powered photoresponse (a responsivity of 268 mA/W and a detectivity of 7.48*1011 Jones). And the rise/decay times are up to 145μs/125μs. Additionally, the detector has a broadband detection capability from visible light to near-infrared. These results provide a promising and simple way to fabricate a MoTe2/WSe2 self-powered broadband photodetector with high performance

Leaders’ capabilities and organizational efficiency: Evidence from the national taxation bureaucracy in China

Tax authority leaders have a significant impact on organizational efficiency, which is mainly manifested in tax collection efficiency. Based on provincial tax administrative data and data on listed companies from 1998 to 2017, we examine the impact of the capabilities of leaders of the National Taxation Bureaucracy (NTB) on tax collection efficiency. We adopt the fixed effects approach and isolate the individual effects of NTB directors as a proxy of leaders’ capabilities. We find that directors with stronger capabilities enhance tax revenue growth and complete tax revenue tasks by affecting corporate income taxes. The findings suggest that more capable directors are found to severely combat tax evasion and avoidance. Specifically, taxable income approved by the NTB, preferential tax policies and tax auditing have been used to combat tax evasion. We also clarify the boundaries of leaders’ capabilities. We provide supportive evidence for leaders’ individual impact on tax collection efficiency and enrich the study of tax collection and administration.

Dual-Wavelength LiDAR with a Single-Pixel Detector Based on the Time-Stretched Method.

In the fields of agriculture and forestry, the Normalized Difference Vegetation Index (NDVI) is a critical indicator for assessing the physiological state of plants. Traditional imaging sensors can only collect two-dimensional vegetation distribution data, while dual-wavelength LiDAR technology offers the capability to capture vertical distribution information, which is essential for forest structure recovery and precision agriculture management. However, existing LiDAR systems face challenges in detecting echoes at two wavelengths, typically relying on multiple detectors or array sensors, leading to high costs, bulky systems, and slow detection rates. This study introduces a time-stretched method to separate two laser wavelengths in the time dimension, enabling a more cost-effective and efficient dual-spectral (600 nm and 800 nm) LiDAR system. Utilizing a supercontinuum laser and a single-pixel detector, the system incorporates specifically designed time-stretched transmission optics, enhancing the efficiency of NDVI data collection. We validated the ranging performance of the system, achieving an accuracy of approximately 3 mm by collecting data with a high sampling rate oscilloscope. Furthermore, by detecting branches, soil, and leaves in various health conditions, we evaluated the system's performance. The dual-wavelength LiDAR can detect variations in NDVI due to differences in chlorophyll concentration and water content. Additionally, we used the radar equation to analyze the actual scene, clarifying the impact of the incidence angle on reflectance and NDVI. Scanning the Red Sumach, we obtained its NDVI distribution, demonstrating its physical characteristics. In conclusion, the proposed dual-wavelength LiDAR based on the time-stretched method has proven effective in agricultural and forestry applications, offering a new technological approach for future precision agriculture and forest management.

Modernizing Land Survey Techniques in East Africa: Challenges and Opportunities

As East Africa undergoes rapid urbanization and economic growth, the need for modernized land survey techniques has become critical. Traditional methods are insufficient for keeping up with the evolving landscape. This article explores the adoption of advanced technologies such as Geographic Information Systems (GIS), remote sensing, and drone technology in land surveying. These innovations promise enhanced accuracy, efficiency, and comprehensive data collection, benefiting urban planning, infrastructure development, and environmental management. However, the transition is challenged by infrastructural deficits, high costs, limited technical expertise, and outdated regulatory frameworks. This article discusses the current technological advancements, challenges, and opportunities for improvement, emphasizing the need for investments in infrastructure, public-private partnerships, capacity building, and regulatory reforms. Vital information were sorted from recent related published database and utilised in writing this paper. Modernizing land survey techniques in East Africa holds significant potential to support sustainable development and effective land management practices. Keywords: Geographic Information Systems (GIS), Remote Sensing, Drone Technology, Land Survey Modernization, East Africa Development

Laser-Constructed Bionic Composite Fog-Collecting Surfaces with Efficient Nucleation Sites and Enhanced Water Transport.

Fog collection effectively alleviates the current freshwater shortage; thus, enhancing its efficiency is crucial. Here, we report a novel bionic fog collection surface (Al@B-V) comprising composite superhydrophobic bumps integrated with superhydrophilic V-channel grooves. This surface, which has efficient fog nucleation points and enhanced water transport capabilities, effectively balances fog capture and water transport during the collection process, thereby achieving high-efficiency fog collection. Compared to ordinary aluminum-based surfaces, Al@B-V achieves a fog collection efficiency of up to 3.08 g·cm-2·h-1, three times higher than the original aluminum-based surface. Furthermore, the V-channel groove proposed in this study exhibits a water transport speed of up to 165 mm·s-1, which is remarkably approximately 80 times faster than the commonly used U-channel groove. Additionally, this V-channel groove can overcome gravity, transporting approximately 10 μL of liquid to the top even when placed at 90° inclination. It can directionally transport 10 μL of liquid over a distance of up to 151 mm on a plane. This novel microgroove design can be effectively applied in various fields, including liquid collection, directional transport, seawater desalination, microfluidics, and drug delivery.

Incineration Innovation: A Path to Efficient and Sustainable Municipal Solid Waste Management in Kuwait

Municipal solid waste management has become a critical global issue due to the rapid increase in waste generation driven by urbanization and population growth. This surge in waste poses significant environmental, social, and health challenges, exacerbated by inefficient recycling and waste-to-energy facilities. Effective waste management requires comprehensive strategies encompassing waste reduction, efficient collection, sorting systems, and advanced recycling and energy recovery technologies. This study highlights the potential of incineration as a waste-to-energy solution, specifically focusing on Kuwait. By analyzing various waste management technologies and their applicability, this study emphasizes the role of incineration in transforming municipal solid waste into electricity, thereby reducing landfill use and environmental impacts. The research includes a detailed review of the existing technologies, a case study on Kuwait’s waste management practices, and an evaluation of the economic and environmental benefits of implementing waste-to-energy incineration. The findings underscore the importance of tailored waste management solutions to address specific regional challenges, promote sustainability, and enhance public health and well-being.

Effect of fluid flow behavior on sustainability and exergy efficiency of solar heat collectors having multiple V‐ribs with gaps

AbstractIn the current numerical study, the viability and sustainability of a solar heat collector (SHC) have been rigorously analyzed through the lens of exergy analysis. The SHC with roughness in the form of symmetrical V‐rib gaps has been selected for detailed numerical investigation. The study focuses on deriving the dominant parameters affecting the performance of the SHC, including the relative gap width (), number of gaps () in the limbs of ribs, and fluid flow Reynolds number, which varied from 4000 to 18,000. The absorber plate with roughness was thoroughly examined to evaluate the losses and irreversibility that persist in the thermal system. The results of the numerical analysis revealed the maximum exergy efficiency to be 3.87%. Furthermore, the study examined the long‐term feasibility of the system, evaluating its sustainability index at a remarkable 1.0319 value, while the magnitude of the waste–energy ratio fetched an impressive score of 0.991. Additionally, the study found that the system has a significant improvement potential of 10.04. Overall, these findings provide critical insights into the performance and sustainability of SHCs, paving the way for future research and development in this crucial field.

Development of a methodology for studying microbiological contamination of office indoor air by analyzing air handling unit filters - Application to a low-energy building

Bioaerosols can alter the air quality, affecting differently people depending on their health status. Methods to sample bioaerosols are limited in terms of sampling time and air volumes. This study evaluated a new methodology to sample airborne microorganisms in buildings, using the air handling unit (AHU) filters and filtration media sampling discs (FMSD). Filtration media with FMSD of different natures were tested at the laboratory, and characterized by their air permeability, particle collection efficiency and the airflow distribution on their surface. Filtration media with FMSD of the same nature had best properties with a sampling particle efficiency of the FMSD of 50 %. This sampling methodology was applied on a building AHU, and FMSD were collected each month during one year. Airborne microorganisms collected by the FMSD were analyzed by culture and nucleic acids based methods (qPCR and Next-Generation sequencing). FMSD methodology gave results for all of those identification methods. Most of the bacteria orders identified by 16 S sequencing were Rhodobacterales (Paracoccus), Pseudomonadales and Cyanobacteria. For fungi, the most represented orders were Agaricales, Polyporales and Hymenochaetales. This sampling methodology has also made it possible to detect small size airborne microorganisms like viruses including two Coronaviruses. This study has shown the potential of using AHU filters to sample the airborne microorganisms in buildings.

Insight into the Impact of Electron Drift Trajectory on Charge Collection in Silicon Drift Detector

The internal electric field distribution is one key design consideration, which affects the charge collection efficiency in silicon drift detectors (SDDs). The internal electrostatic potential distributions along SDD front and back surfaces, which are determined by the applied voltages at cathode electrodes, define the final internal field distribution. Front-back bias coupling leads to the complexity of electrode structure design and voltage tuning. Device simulation is performed to investigate the performance of SDDs with varied bias voltages. When the cathode bias is −40 V with the first ring bias of −15 V and the outermost ring bias of −80 V, the detector is biased with a uniform electric field distribution, favorable electron drift trajectories. The simulation results provide new insight into the influence of internal electric field and electron drift trajectories on the charge collection efficiency. According to the analysis of simulation results, a 2000 × 2000 μm area concentric silicon drift detector was designed and fabricated. The electrical characteristics of the designed detectors were studied to show the validity of the proposed device design methodology. The internal electric field distribution and electron drift trajectories can be tuned to improve the charge collection efficiency.

Performance and Design Optimization of Solar Collectors

The objective of the present work was to conduct a comparative analysis of solar collectors. The experimental set-up consists of two flat plate solar collectors, the first collector was with a fixed surface tilted at 30о towards the South, and the second one was equipped with dual-axis rotation system. A programmable chronological tracker was used to control the motion of the moving collector. An experimental programme was performed to investigate the effect of the sun tracking system usage on the collector efficiency. The study includes development of a 3-D mathematical model of the system and extensive numerical simulation, based on the computational fluid dynamics (CFD) approach. The main aim of the modelling is to provide information on heat transfer, and to numerically simulate the heat transfer performances and the energy capture capabilities of the fixed and moving collectors in various operating modes. The comparative analysis shows that there is a good agreement between the experimental and numerically predicted results for different running conditions, and the presented modelling approach can be used for further investigations, including more complex problems.

Evaluation of greenhouse gas emission and reduction potential of high-food-waste-content municipal solid waste landfills: A case study of a landfill in the east of China

This study proposes a comprehensive evaluation method based on a two-stage model to assess greenhouse gas (GHG) emissions and reductions in high-food-waste-content (HFWC) municipal solid waste (MSW) landfills. The proposed method considers typical processes such as fugitive landfill gas (LFG), LFG collection, flaring, power generation, and leachate treatment. A case study of an HFWC MSW landfill in eastern China is considered to illustrate the evaluation. The findings revealed that the GHG emissions equivalent of the case landfill amounted to 21.23 million tons from 2007 to 2022, averaging 1.03 tons CO2-eq per ton of MSW. There was a potential underestimation of LFG generation at the landfill site during the initial stages, which led to delayed LFG collection and substantial fugitive LFG emissions. Additionally, the time distribution of GHG emissions from HFWC MSW was significantly different from that of low-food-waste-content (LFWC) MSW landfills, with peak emissions occurring much earlier. Owing to the rapid degradation characteristics of HFWC MSW, the cumulative LFG production of the landfill by 2022 (2 years after the final cover) was projected to reach 77 % of the total LFG potential. In contrast, it would take until 2030 for LFWC MSW landfills to reach this level. Furthermore, various scenarios were analyzed, in which if the rapid LFG generation characteristics of HFWC MSW are known in advance, and relevant facilities are constructed ahead of time, the collection efficiency can be improved from 31 % to over 78 %, resulting in less GHG emissions.

Delineation of the impact on temporal behaviors of off-axis photoemission in an ultrafast electron microscope

Efforts to push the spatiotemporal imaging-resolution limits of femtosecond laser-driven ultrafast electron microscopes (UEMs) to the combined angstrom–fs range will benefit from stable sources capable of generating high bunch charges. Recent demonstrations of unconventional off-axis photoemitting geometries are promising, but connections to the observed onset of structural dynamics are yet to be established. Here we use the in-situ photoexcitation of coherent phonons to quantify the relative time-of-flight (r-TOF) of photoelectron packets generated from the Ni Wehnelt aperture and from a Ta cathode set-back from the aperture plane. We further support the UEM experiments with particle-tracing simulations of the precise electron-gun architecture and photoemitting geometries. In this way, we measure discernible shifts in electron-packet TOF of tens of picoseconds for the two photoemitting surfaces. These shifts arise from the impact that the Wehnelt-aperture off-axis orientation has on the electron-momentum distribution, which modifies both the collection efficiency and the temporal-packet distribution relative to on-axis emission. Future needs are identified; we expect this and other developments in UEM electron-gun configuration to expand the range of material phenomena that can be directly imaged on scales commensurate with fundamental structural dynamics.

Enhancing thermal energy and exergy harvesting in concentrated solar power systems using graphene-ZrO2/water hybrid nanofluid: An experimental study

Recent research has witnessed a significant increase in studies investigating the impact of nanofluids on enhancing the efficiency of sustainable energy systems. According to the details that were provided, the present study aims to enhance the heat and exergy efficiency of parabolic trough solar collectors (PTSCs) by using a water-based hybrid nanofluid with dispersed Graphene-ZrO2 at various volume concentrations (water, 0.05 %, 0.075 %, 0.1 %, and 0.125 %) as the working fluid. This research employs the hybrid nanofluid to improve heat transfer characteristics within the C.S.P. system, enhancing thermal energy extraction and exergy utilization. The proposed nanofluid underwent Fourier transform infrared spectroscopy (FTIR) analysis to determine its transmission spectrum across various frequencies. X-ray diffraction analysis was also conducted to elucidate the structural characteristics of two identical water and hybrid working fluids. The maximum thermal efficiency of 68.7 % was achieved for the PTSC system by adding 0.125 % of ZrO2 nanoparticle concentration with a mass flow rate of 3 L/min. Exergy efficiency was found for maximum volume concentration compared to distilled water fluid. Experimental results indicate significant improvements in thermal energy (68.72 %) and exergy harvesting efficiency (16.7 %), demonstrating the potential of graphene-ZrO2/Water hybrid nanofluids as a viable solution for enhancing the performance of C.S.P. systems.

Internet of Things Enhanced Maritime Robot for Ocean Waste Cleanup

Plastic pollution is a major environmental concern, particularly in aquatic habitats. The accumulation of floating debris in water bodies caused by plastic pollution negatively impacts ecosystems, aquatic life, and water quality. The objective of this proposed study is to develop a remote-controlled boat equipped with sensors for measuring water quality and an efficient waste collection system. These sensors provide important information about the environmental conditions of the water body by measuring important factors like pH, dissolved oxygen, and turbidity. The data on water quality helps identify the regions that require immediate attention to prevent and manage pollution, as well as assess the overall health of the ecosystem. The primary goal of the research is to significantly reduce the plastic waste in marine areas, promote sustainable practices, and raise public awareness about the need to address marine pollution, ultimately enhancing a healthier marine ecosystem.

DiSA-CF: A distance-integrated self-attention model for collaborative filtering in web service recommendation

The ubiquity of the Internet of Things (IoT) across diverse applications underscore its pivotal role in seamlessly integrating physical devices to facilitate efficient data collection, analysis, and automation. Consequently, ensuring the Quality of Service (QoS) emerges as a critical imperative. While numerous studies have proposed methodologies focusing on resource optimization, network management, and data processing techniques, several previous approaches to QoS prediction may face constraints in the Internet of Things (IoT) environment, where the dynamic nature of IoT environments demands predictive models capable of adapting to varying conditions. Integrating user and service location data into QoS prediction models is paramount, as it enables personalized service delivery tailored to the user’s specific context, thus enhancing the user experience and overall system performance. This paper presents a novel approach to QoS prediction in IoT, harnessing self-attention and collaborative filtering (CF) techniques while incorporating location-based features such as distance from the user to the service. Experimental evaluations on benchmark datasets reveal that our proposed model improves prediction accuracy by up to 7 % compared to existing methods, underscoring its efficacy in enhancing QoS provisioning in IoT environments.

Buzz pollination: Bee bites and floral vibrations

Certain bees bite tubular anthers while contracting their flight muscles. This floral sonication ejects pollen grains that the bees collect as larval food. Bees bite and buzz simultaneously. A new study shows that where and how they bite is essential for efficient pollen collection.

Potential Water Collection From Air by Chloride Perovskites.

Directly capturing water from the air has become a compelling strategy to secure water resources. Yet, challenges persist with sorption-based hygroscopic materials, such as inadequate water adsorption efficiency, material degradation post-adsorption, and the need for energy input during water collection. This study introduces an alternative category of sorbent materials potentially for atmospheric water harvesting-metal chloride perovskites-that exhibit spontaneous water vapor adsorption and liquid water collection. This water uptake capability stems from the uncoordinated polar ions that form hydrogen bonds with water molecules, while the cubic lattice imparts a solid framework ensuring structural stability and inhibiting hydrolysis. The methylammonium lead chloride perovskite pellets exhibit efficient water collection performance, with a record absorption rate of 0.841 L m-2 h-1 and a total water collection of 3.675 L m-2 within a 7-h cycle. This initiative attempts to provide a new material class candidate for the potential application of passive atmospheric water harvesting.

Ética y Eficiencia

In this paper, I intend to demonstrate that there is a causal and necessary relationship between ethical behavior and the individual and collective efficiency of human beings. To do this, I will first develop the argument that ethical behavior is part of human nature and not merely a social construct. Then, I will establish its relationship with the form of [1]social organization that ensures efficiency in achieving collective goals. This ethics-efficiency relationship breaks with the traditional concept of effective leadership, where individual interests and authoritarian behavior prevail, and promises to become the new paradigm of successful social organizations, be they businesses, NGOs, educational institutions, sports teams, etc.