Collection efficiency of a monitor parallel plate ionization chamber for pencil beam scanning proton therapy

The collection efficiency of monitor parallel plate ionization chambers is the main uncertainty in the beam control of pencil beam scanning systems.Existing calculation methods for collection efficiency in photon or passive scattering proton systems have not considered the characteristics of non-uniform charge density in pencil beam scanning systems.In this study,Boag’s theory was applied to a proton pencil beam scanning system.The transverse distribution of charge density in the ionization chamber was considered to be a Gaussian function and an analytical solution was derived to calculate collection efficiency in the beam spot area.This calculation method is called the integral method and it was used to investigate the effects of beam parameters on collection efficiency.It was determined that collection efficiency is positively correlated with applied voltage,beam size,and beam energy,but negatively correlated with beam current intensity.Additionally,it was confirmed that collection efficiency is improved when the air filling the monitor parallel plate ionization chamber is replaced with nitrogen.

Phylogeography and Characteristics of Phosphorus Efficiency of Secondary Core Collection for Rice Landraces in Yunnan Province

[Objective] The paper was to explore the causes of phosphorus(P)efficiency of rice in Yunnan Province,and to provide strategy for ecological and environmental protection.[Method]Using 703 accessions of secondary core collections from 16 prefectures of five regions in Yunnan Province,two treatments of low available P(6.26mg/kg)versus normal P(available P 40mg/kg),and invalid P(available P 0.02 mg/kg)versus normal P(available P 70 mg/kg)were set,and zonal characteristics of phosphorus efficiency and the activation characteristics of invalid P of rice landraces were investigated.[Result] Phosphorus efficiency and the activation characteristics of invalid P in soils from rice landraces of Yunnan Province had the similar identification indexes,viz.the relative indexes of four traits(tillering ability or effective panicle,root weight,biomass,and straw weight)could be the screening indexes of gene type of secondary core collection with phosphorus efficiency,which also reflected the zonal characteristics of phosphorus efficiency and the activation characteristics of invalid P in soils of 16 prefectures among five regions.On the contrary,the relative panicle length,node length under panicle,leaf length,leaf width and plant height could only be the assistant indexes of identification for phosphorus efficiency.There were similar zonal characteristics between phosphorus efficiency and the activation characteristics of invalid P in soils of rice landraces in Yunnan Province.[Conclusion] The study had great importance to the conservation and utilization of biological diversity,which would make contribution to second green revolution of "less input,multiple output,promote health,and protect the environment".

Effects of Different Rainwater Diversion Patterns on Rainwater Collection Efficiency and Water Utilization Efficiency in Cornfield

Four rainwater diversion patterns including undisturbed soil ditch （T1）, slope compaction （T2）, asbestos sheet covering after compac- tion （T3） and plastic film covering after compaction （T4） were set in cornfield in arid areas of Yunnan Province, and effects of various patterns on rainwater collection efficiency, water utilization efficiency and corn yield were studied. The results shows that rainwater collection efficiency, water utilization efficiency and corn yield of the four diversion patterns presented the same trend, namely T4 〉T3 〉T2 〉T1. Overall, rainwater collection efficiencies of the four diversion patterns ranged from 41.7% to 58.7% ; compared with T1, water utilization efficiencies of T2 ,T3 and T4 increased by 34.9%, 53.5% and 92.5%, and maize yields of them improved by 1 767.0, 1 981.5 and 2 385.0 kg/hm2.

Enhancement of Cathode Dust Collection and its Application in Improving the Efficiency of Dry Electrostatic Precipitator

As the main equipment of flue gas dedusting in coal fired boiler,electrostatic precipitator(ESP)can meet the requirements of emission standard for air pollutants from coal-fired power plants through improving the efficiency of ESP and combining with desulfurization system while not installing wet ESP(WESP).This paper introduces the modifications of ESP cathode structure to improve the efficiency of dust collection by reducing the secondary dust loss at cathode.The application of cathode dust collection provides a reference for the improvement of ESP dust collection efficiency.

Comparison of Copepod Collection Efficiencies by Three Commonly Used Plankton Nets: A Case Study in Bohai Sea, China

Abstract Selection of net with a suitable mesh size is a key concern in the quantitative assessment of zooplankton, which is cru- cial to understand pelagic ecosystem processes. This study compared the copepod collecting efficiency of three commonly used plankton nets, namely, the China standard coarse net （505 gm mesh）, the China standard fine net （77 gin）, and the WP-2 net （200 μm） The experiment was performed at six stations in the Bohai Sea during the autumn of 2012. The coarse net substantially un- der-sampled small individuals （body widths 〈 672 gm） and led to the lowest species number in each tow, whereas the fine net col- lected all small copepod species but failed to collect rare species. The WP-2 net appeared to be a compromise of the two other nets, collecting both small copepods and rare species. The abundance of copepods collected by the coarse net （126.4±86.5 indm-3） was one to two orders of magnitude lower than that by the WP-2 net （5802.4 ± 2595.4 indm3）, and the value of the fine net （11117.0±4563.41 indm-3） was nearly twice that of the WP-2 net. The abundance of large copepods （i.e., adult Calanus sinicus） in the three nets showed no significant differences, but the abundance of small copepods declined with decreasing mesh size. The dif- ference in abundance resulted from the under-sampling of small copepods with body widths 〈 672 μm and 〈 266μm by the coarse and WP-2 nets, respectively.

Energy-Efficient Underwater Data Collection:A Q-Learning Based Approach

Underwater data collection is an importance part in the process of network monitoring,network management and intrusion detection.However,the limited-energy of nodes is a major challenge to collect underwater data.The solution of this problem are not only in the hands of network topology but in the hands of path of autonomous underwater vehicle(AUV).With the problem in hand,an energy-efficient data collection scheme is designed for mobile underwater network.Especially,the data collection scheme is divided into two phases,i.e.,routing algorithm design for sensor nodes and path planing for AUV.With consideration of limited-energy and network robustness,Q-learning based dynamic routing algorithm is designed in the first phase to optimize the routing selection of nodes,through which a potential-game based optimal rigid graph method is proposed to balance the trade-off between the energy consumption and the network robustness.With the collected data,Q-learning based path planning strategy is proposed for AUV in the second phase to find the desired path to gather the data from data collector,then a mode-free tracking controller is developed to track the desired path accurately.Finally,the performance analysis and simulation results reveal that the proposed approach can guarantee energy-efficient and improve network stability.

Efficiency of collective myosin Ⅱ motors studied with an elastic coupling power-stroke ratchet model

We proposed a modified ratchet model including power-stroke and elastic coupling to study the efficiency of collective non-processive motors such as myosin Ⅱ in muscle. Our theoretical results are in good agreement with the experimental data. Our study not only reveals that the maximum efficiency depends on elasticity and is independent of transition rates but also indicates that the parameters fitted to fast muscle are different from those fitted to a slow one. The latter may imply that the structure of the fast muscle is different from that of the slow one. The main reason that our model succeeds is that velocity in this model is an independent variable.

Energy-Efficient Mobile Data Collection Adopting Node Cooperation in an Underwater Acoustic Sensor Network

This paper considers an underwater acoustic sensor network with one mobile surface node to collect data from multiple underwater nodes,where the mobile destination requests retransmission from each underwater node individually employing traditional automatic-repeat-request(ARQ) protocol.We propose a practical node cooperation(NC) protocol to enhance the collection efficiency,utilizing the fact that underwater nodes can overhear the transmission of others.To reduce the source level of underwater nodes,the underwater data collection area is divided into several sub-zones,and in each sub-zone,the mobile surface node adopting the NC protocol could switch adaptively between selective relay cooperation(SRC) and dynamic network coded cooperation(DNC) .The difference of SRC and DNC lies in whether or not the selected relay node combines the local data and the data overheard from undecoded node(s) to form network coded packets in the retransmission phase.The NC protocol could also be applied across the sub-zones due to the wiretap property.In addition,we investigate the effects of different mobile collection paths,collection area division and cooperative zone design for energy saving.The numerical results showthat the proposed NC protocol can effectively save energy compared with the traditional ARQ scheme.

Study on Collecting Efficiency of Lube-oil Filtration Media

We made an experimental study and analysis on the relationships between filtration collecting efficiency and porosity, fiber diameter, and particles diameters for differential porosity media when fibrous media collecting lube-oil. The influencing extent of porosity, dust concentration, and velocity impacting on collecting efficiency were researched by orthogonal experimental test. The results showed that porosity had the best salience affection on collecting efficiency, and the affection of velocity and dust concentration was less. The main factors of impacting on collecting efficiency were porosity, fiber diameter, particles diameter, dust concentration, filtration time and filtration velocity. The correlation formula between collecting efficiency and porosity, aperture diameter, fiber diameter, particles diameter, the thickness of media, and filtration time was obtained. It can forecast the collecting efficiency of lube-oil filtration media and provide a guide for selecting suitable fibrous filtration media.

Joint UAV 3D deployment and sensor power allocation for energy-efficient and secure data collection

Unmanned aerial vehicles(UAVs) are advantageous for data collection in wireless sensor networks(WSNs) due to its low cost of use,flexible deployment,controllable mobility,etc. However,how to cope with the inherent issues of energy limitation and data security in the WSNs is challenging in such an application paradigm. To this end,based on the framework of physical layer security,an optimization problem for maximizing secrecy energy efficiency(EE) of data collection is formulated,which focuses on optimizing the UAV’s positions and the sensors’ transmit power. To overcome the difficulties in solving the optimization problem,the methods of fractional programming and successive convex approximation are then adopted to gradually transform the original problem into a series of tractable subproblems which are solved in an iterative manner. As shown in simulation results,by the joint designs in the spatial domain of UAV and the power domain of sensors,the proposed algorithm achieves a significant improvement of secrecy EE and rate.

Bipolar charged aerosol agglomeration and collection by a two-zone agglomerator

In older to collect fine particles more efficiently, a new-type electrostatic agglomerator with two zones was developed. The distinguishing feature of this electrostatic agglomerator is that the particles are bipolarly charged and coagulated in the same alternating electric field simultaneously. The silica flour with 2 fun mass median diameter and the smoke from burning wood powder were used as test aerosol. The comparison experimental results have shown that when the mean electric field is 4 kV/cm the collection efficiency of the new electrostatic agglomerator was 98.2% for silica flour and 67.4% for wood powder smoke, Under the same experimental condition. the collection efficiency of the electrostatic agglomerator with three zones was 97.4% for collecting silica flour and the collection efficiency of the electrostatic precipitator was 56.3% for wood powder smoke.

Energy Aware Data Collection with Route Planning for 6G Enabled UAV Communication

With technological advancements in 6G and Internet of Things(IoT), the incorporation of Unmanned Aerial Vehicles (UAVs) and cellularnetworks has become a hot research topic. At present, the proficient evolution of 6G networks allows the UAVs to offer cost-effective and timelysolutions for real-time applications such as medicine, tracking, surveillance,etc. Energy efficiency, data collection, and route planning are crucial processesto improve the network communication. These processes are highly difficultowing to high mobility, presence of non-stationary links, dynamic topology,and energy-restricted UAVs. With this motivation, the current research paperpresents a novel Energy Aware Data Collection with Routing Planning for6G-enabled UAV communication (EADCRP-6G) technique. The goal of theproposed EADCRP-6G technique is to conduct energy-efficient cluster-baseddata collection and optimal route planning for 6G-enabled UAV networks.EADCRP-6G technique deploys Improved Red Deer Algorithm-based Clustering (IRDAC) technique to elect an optimal set of Cluster Heads (CH) andorganize these clusters. Besides, Artificial Fish Swarm-based Route Planning(AFSRP) technique is applied to choose an optimum set of routes for UAVcommunication in 6G networks. In order to validated whether the proposedEADCRP-6G technique enhances the performance, a series of simulationswas performed and the outcomes were investigated under different dimensions.The experimental results showcase that the proposed model outperformed allother existing models under different evaluation parameters.

Artificial Intelligence-Enabled Cooperative Cluster-Based Data Collection for Unmanned Aerial Vehicles

In recent times,sixth generation(6G)communication technologies have become a hot research topic because of maximum throughput and low delay services for mobile users.It encompasses several heterogeneous resource and communication standard in ensuring incessant availability of service.At the same time,the development of 6G enables the Unmanned Aerial Vehicles(UAVs)in offering cost and time-efficient solution to several applications like healthcare,surveillance,disaster management,etc.In UAV networks,energy efficiency and data collection are considered the major process for high quality network communication.But these procedures are found to be challenging because of maximum mobility,unstable links,dynamic topology,and energy restricted UAVs.These issues are solved by the use of artificial intelligence(AI)and energy efficient clustering techniques for UAVs in the 6G environment.With this inspiration,this work designs an artificial intelligence enabled cooperative cluster-based data collection technique for unmanned aerial vehicles(AECCDC-UAV)in 6G environment.The proposed AECCDC-UAV technique purposes for dividing the UAV network as to different clusters and allocate a cluster head(CH)to each cluster in such a way that the energy consumption(ECM)gets minimized.The presented AECCDC-UAV technique involves a quasi-oppositional shuffled shepherd optimization(QOSSO)algorithm for selecting the CHs and construct clusters.The QOSSO algorithm derives a fitness function involving three input parameters residual energy of UAVs,distance to neighboring UAVs,and degree of UAVs.The performance of the AECCDC-UAV technique is validated in many aspects and the obtained experimental values demonstration promising results over the recent state of art methods.

Optimal Design of Aperture Illuminations for Microwave Power Transmission with Annular Collection Areas

This work presents an optimal design method of antenna aperture illumination for microwave power transmission with an annular collection area.The objective is to maximize the ratio of the power radiated on the annular collection area to the total transmitted power.By formulating the aperture amplitude distribution through a summation of a special set of series,the optimal design problem can be reduced to finding the maximum ratio of two real quadratic forms.Based on the theory of matrices,the solution to the formulated optimization problem is to determine the largest characteristic value and its associated characteristic vector.To meet security requirements,the peak radiation levels outside the receiving area are considered to be extra constraints.A hybrid grey wolf optimizer and Nelder–Mead simplex method is developed to deal with this constrained optimization problem.In order to demonstrate the effectiveness of the proposed method,numerical experiments on continuous apertures are conducted;then,discrete arrays of isotropic elements are employed to validate the correctness of the optimized results.Finally,patch arrays are adopted to further verify the validity of the proposed method.

Recombination-induced voltage-dependent photocurrent collection loss in CdTe thin film solar cell

Recently, the efficiency of CdTe thin film solar cell has been improved by using new type of window layer Mg_(x)Zn_(1-x)O(MZO). However, it is hard to achieve such a high efficiency as expected. In this report a comparative study is carried out between the MZO/CdTe and CdS/CdTe solar cells to investigate the factors affecting the device performance of MZO/CdTe solar cells. The efficiency loss quantified by voltage-dependent photocurrent collection efficiency(ηC(V′)) is 3.89% for MZO/CdTe and 1.53% for CdS/CdTe solar cells. The higher efficiency loss for the MZO/CdTe solar cell is induced by more severe carrier recombination at the MZO/CdTe p-n junction interface and in CdTe bulk region than that for the CdS/CdTe solar cell. Activation energy(Ea) of the reverse saturation current of the MZO/CdTe and CdS/CdTe solar cells are found to be 1.08 e V and 1.36 e V, respectively. These values indicate that for the CdS/CdTe solar cell the carrier recombination is dominated by bulk Shockley-Read-Hall(SRH) recombination and for the MZO/CdTe solar cell the carrier recombination is dominated by the p-n junction interface recombination. It is found that the tunneling-enhanced interface recombination is also involved in carrier recombination in the MZO/CdTe solar cell. This work demonstrates the poor device performance of the MZO/CdTe solar cell is induced by more severe interface and bulk recombination than that of the CdS/CdTe solar cell.

Modeling Submicron Particles Collection in Laminar Forced Convection Gas Flow by a Rectangular Venturi Scrubber

Venturi scrubbers are usually used for large particles cleaning in turbulent gaseous flow. In this work, submicron particles scrubbing in laminar forced convection dusty air flow in a rectangular venturi scrubber have been numerically simulated. Hydrodynamics effects and scrubbing process are investigated in detail. Results are presented as flow velocity, axial pressure, streamlines pattern, particles and droplets mass fraction profile, and collect efficiency. They show that venturi scrubbers can be efficient for submicron particles scrubbing. In fact, a better collect efficiency is obtained at high particles-droplets residence time, high ratio droplets concentration/particles concentration, low venturi diameter ratioand low Reynolds numbers. There is a critical Reynolds number value for which the collect efficiency becomes very low and tends to be constant.

Collecting aerosol in airflow with a magnetically stabilized fluidized bed

A magnetically stabilized fluidized bed (MSB) is a highly efficient filter that takes the advantage of both fluidized beds and fixed beds. This paper presents the research to collect aerosol in airflow with a MSB. The filtering model of MSB is established with its parameters including magnetic Geld intensity, gas superficial velocity, average grain-size, and bed height on the collection efficiency of MSB. The model is verified by experiments.

Numerical study of collection efficiency and heat-transfer characteristics of packed granular filter

The collection mechanism and heat-transfer characteristics of a packed granular filter were investigated using a three-dimensional randomly packed granular filter model. The bridging method was introduced to optimize the grids of contact points between granules. The influences of granular bed depth, gas velocity, and gas temperature on grade collection efficiency were investigated. The results indicated that a decrease of temperature improved collection efficiency when the particle diameter was greater than 5 |xm. The grade collection efficiency maintained a stable value when the Stokes number, St, was less than 0.009, but increased linearly with ig(St) when St > 0.009. A logarithmic mean temperature difference method was used to obtain overall heat-transfer coefficients of gas-solid two-phase flow through the packed granular filter. The results showed that convective heat transfer was enhanced due to the intro-duction of solid particles in the bed. The overall heat-transfer coefficient increased approximately linearly with an increase in particle loading ratio. The Nusselt number was related to the Reynolds number, the Archimedes number, and the particle loading ratio.