The nonlinear space charge effect of a bunched beam with Gaussian distribu-tion in the longitudinal direction is discussed.Some useful formulae are derived for cal-culating the potential induced by a cylinder model of...The nonlinear space charge effect of a bunched beam with Gaussian distribu-tion in the longitudinal direction is discussed.Some useful formulae are derived for cal-culating the potential induced by a cylinder model of space charge in the waveguide of alinac with different combinations of density distribution:Gaussian distribution in thelongitudinal direction versus Kapchinskij Vladimirskij,waterbag,parabolic andGaussian distribution in the transverse direction,rcspectively.展开更多
A novel bunched cerium oxide(CeO_(2))was prepared and its binary composite material with multi-walled carbon nanotubes presented an excellent microwave absorbing properties.The morphology,structure,and absorbing prope...A novel bunched cerium oxide(CeO_(2))was prepared and its binary composite material with multi-walled carbon nanotubes presented an excellent microwave absorbing properties.The morphology,structure,and absorbing properties of the composite material were investigated.It was found that the minimum reflection loss(RL)of the composite material at 15.79 GHz was−45.7 dB when the thickness was 5.5 mm.It was worth noting that when the composite material was in the thickness range of 5.0-7.5 mm and the frequency was 11.36-17.77 GHz,the electromagnetic wave RL was<−30 dB,which illustrated that the composite material had a good absorbing effect over a wide thickness range.The results of the study contributed to the design and preparation of efficient microwave absorbing materials(MAM)with rare earth oxide composites and their applications,which demonstrated the importance of new composites with special structures in the field of MAM.展开更多
[Background]High harmonic cavities are widely used in electron storage rings to lengthen thebunch,lower the bunch peak current,thereby reducing the IBS effect,enhancing the Touschek lifetime,as well asproviding Landau...[Background]High harmonic cavities are widely used in electron storage rings to lengthen thebunch,lower the bunch peak current,thereby reducing the IBS effect,enhancing the Touschek lifetime,as well asproviding Landau damping,which is particularly important for storage rings operating with ultra-low emittance or atlow beam energy.[Purpose]To further increase the bunch length without additional hardware costs,the phasemodulation in a dual-RF system is considered.[Methods]In this paper,turn-by-turn simulations incorporating randomsynchrotron radiation excitation are conducted,and a brief analysis is presented to explain the bunch lengtheningmechanism.[Results]Simulation results reveal that the peak current can be further reduced,thereby mitigating IBSeffects and enhancing the Touschek lifetime.Although the energy spread increases,which tends to reduce thebrightness of higher-harmonic radiation from the undulator,the brightness of the fundamental harmonic can,in fact,beimproved.展开更多
The rapid cycling synchrotron(RCS)at the China spallation neutron source operates as a high-intensity proton accelerator.The coupled bunch instability was observed during RCS beam commissioning,which significantly lim...The rapid cycling synchrotron(RCS)at the China spallation neutron source operates as a high-intensity proton accelerator.The coupled bunch instability was observed during RCS beam commissioning,which significantly limited the beam power.To investigate the dynamics of instability under an increased beam power,a pulsed octupole magnet with a gradient of 900 T/m^(3) was developed.The magnet system integrated an octupole magnet with a pulsed power supply.The field was carefully measured to examine the performance before its installation into the tunnel.After the installation of the magnets,beam measurements were performed to confirm the effectiveness of the instability mitigation on an actual proton beam.The measurement results show that the instability can be suppressed using the pulsed octupole magnet,particularly at the highenergy stage in an acceleration cycle,meeting the requirements for stable operation of the accelerator.Additionally,when the instability is completely suppressed through chromaticity optimization,octupole magnets can significantly enhance the RCS transmission efficiency,which is crucial for controlling beam loss.The pulsed octupole magnet offers significant progress in beam stability in the RCS,providing valuable experience for further beam power enhancement.展开更多
A super-radiant terahertz free-electron laser(THz-FEL)light source was developed for the first time in Thailand and Southeast Asia at the PBP-CMU Electron Linac Laboratory(PCELL)of Chiang Mai University.This radiation...A super-radiant terahertz free-electron laser(THz-FEL)light source was developed for the first time in Thailand and Southeast Asia at the PBP-CMU Electron Linac Laboratory(PCELL)of Chiang Mai University.This radiation source requires relatively ultrashort electron bunches to produce intense coherent THz pulses.Three electron bunch compression processes are utilized in the PCELL accelerator system comprising pre-bunch compression in an alpha magnet,velocity bunching in a radio-frequency(RF)linear accelerator(linac),and magnetic bunch compression in a 180°acromat system.Electron bunch compression in the magnetic compressor system poses considerable challenges,which are addressed through the use of three quadrupole doublets.The strengths of the quadrupole fields significantly influence the rotation of the beam line longitudinal phase space distribution along the bunch compressor.Start-to-end beam dynamics simulations using the ASTRA code were performed to optimize the electron beam properties for generating super-radiant THz-FEL radiation.The operational parameters considered in the simulations comprise the alpha magnet gradient,linac RF phase,and quadrupole field strengths.The optimization results show that 10-16MeV femtosecond electron bunches with a low energy spread(~0.2%),small normalized emittance(~15πmm·mrad),and high peak current(165-247A)can be produced by the PCELL accelerator system at the optimal parameters.A THz-FEL with sub-microjoule pulse energies can thus be obtained at the optimized electron beam parameters.The physical and conceptual design of the THz-FEL beamline were completed based on the beam dynamics simulation results.The construction and installation of this beamline are currently underway and expected to be completed by mid-2024.The commissioning of the beamline will then commence.展开更多
The use of organic fertilizers is less expensive and advantageous for both the development of the plant and the sanitation of the environment. This is why this investigation aims to promote the ash from emptying of oi...The use of organic fertilizers is less expensive and advantageous for both the development of the plant and the sanitation of the environment. This is why this investigation aims to promote the ash from emptying of oil mill boilers as a source of organic fertilization in the production of palm bunches. To do this, different doses of oil mill boiler emptying ash were tested on oil palms in production. The results showed that the oil palms responded favorably regardless of the dose of oil mill boiler emptying ash. Thus, the comparison of the different doses Tv1 (1 kg), Tv2 (1.5 kg), Tv3 (2 kg), Tv4 (3 kg), Tv5 (4 kg), Tv6 (5 kg) and Tv7 (7 kg) showed that the high doses led to an increase in the weight of the bunches. Better still, the Tv6 treatment at a dose of 5 kg/tree proved to be optimal for good production of palm bunches with a gain of 73.9% compared to the treatment without oil mill boiler emptying ash (absolute control).展开更多
Activated charcoals were synthesized from sugar palm bunches(SPB)of the native tree of Arenga longipes in Indonesia.The synthesized activated charcoal(AC)was characterized,and utilized as an absorbent for heavy metals...Activated charcoals were synthesized from sugar palm bunches(SPB)of the native tree of Arenga longipes in Indonesia.The synthesized activated charcoal(AC)was characterized,and utilized as an absorbent for heavy metals(lead/Pb and copper/Cu)through thermal activation.The synthesis of AC was accomplished through furnace activation at temperatures of 500℃,600℃,700℃,and 800℃.Acid chlorides were blended with the SPB-AC samples at 5%impregnation level and subsequently subjected to washing for activation,resulting in the elimination of volatile substances and ash content,which facilitates the development of a porous structure in the activated charcoal.The proximate analysis results indicated a reduction in weight and moisture content with an increase in activation temperature.The C-O,C=C,O-H stretching chains were not visible in the SPB-AC,indicating that the chains were broken after activation.The treatments at 600℃ and 700℃ exhibited superior thermal stability relative to the others.Moreover,there was a notable reduction in the signal strength of low-crystallinity amorphous carbon,indicating that the high-temperature treatment substantially altered the structural characteristics of the crystal.The SPB-AC produced at 700℃ exhibited a primarily microporous architecture,characterized by a maximal surface area,reduced total pore volume,and small particle size.In conclusion,elevating the activation temperature to 700℃ leads to notable improvement in the adsorption of Pb(91.61%)and Cu(95.19%)metals.展开更多
Industrial linear accelerators often contain many bunches when their pulse widths are extended to microseconds.As they typically operate at low electron energies and high currents,the interactions among bunches cannot...Industrial linear accelerators often contain many bunches when their pulse widths are extended to microseconds.As they typically operate at low electron energies and high currents,the interactions among bunches cannot be neglected.In this study,an algorithm is introduced for calculating the space charge force of a train with infinite bunches.By utilizing the ring charge model and the particle-in-cell(PIC)method and combining analytical and numerical methods,the proposed algorithm efficiently calculates the space charge force of infinite bunches,enabling the accurate design of accelerator parameters and a comprehensive understanding of the space charge force.This is a significant improvement on existing simulation software such as ASTRA and PARMELA that can only handle a single bunch or a small number of bunches.The PIC algorithm is validated in long drift space transport by comparing it with existing models,such as the infinite-bunch,ASTRA single-bunch,and PARMELA several-bunch algorithms.The space charge force calculation results for the external acceleration field are also verified.The reliability of the proposed algorithm provides a foundation for the design and optimization of industrial accelerators.展开更多
The utilisation of sugar palm bunches-charcoal briquettes(SPB-CB)represents a significant advancement in biomass energy.This study aimed to analyse the properties of charcoal briquettes produced from SPB(Arenga longip...The utilisation of sugar palm bunches-charcoal briquettes(SPB-CB)represents a significant advancement in biomass energy.This study aimed to analyse the properties of charcoal briquettes produced from SPB(Arenga longipes).The experiment involved categorising the dimensions of charcoal powder into three specific particle sizes:20-40 mesh,40-60 mesh,and particles that could pass through a 60-mesh screen.The charcoal powder will be combined with tapioca as a binding agent at three specific concentrations:11%,13%,and 15%.The research findings indicate that the samples underwent 60 mesh passes achieved the maximum briquette density,with an average value of 0.58 g/cm^(3).The highest attainable compressive strength sample value was 27.52 kgf/cm^(2),which was attained by employing 60 mesh size and 15%adhesive concentration.The calorimetric investigation showed that SPB-charcoal had the highest calorific value of 25.88 MJ/kg,while the SPB-CB had a little lower caloric value of 24.64 MJ/kg.The ash content and volatile matter values showed that the briquettes with the lowest ash content had values of 10.49%and 32.65%,respectively.Furthermore,the carbon fixation values varied between 16.65%and 52.36%.Thermogravimetric analysis indicates that charcoal derived from SPB exhibits superior thermal characteristics compared to charcoal briquettes.However,thermal properties of SPB charcoal do not show significant differences when compared to charcoal briquettes that have been processed with a mesh size of 20-40 and include 11%adhesive.According to this research,it may be inferred that charcoal briquettes made from sugar palm bunches meet the requirements specified in SNI 01-6235-2000.展开更多
The development of the bioplastics industry addresses critical issues such as environmental pollution and food safety concerns.However,the industrialization of bioplastics remains underdeveloped due to challenges such...The development of the bioplastics industry addresses critical issues such as environmental pollution and food safety concerns.However,the industrialization of bioplastics remains underdeveloped due to challenges such as high production costs and suboptimal material characteristics.To enhance these characteristics,this study investigates bioplastics reinforced with Nanocrystalline Cellulose(NCC)derived from Oil Palm Empty Fruit Bunches(OPEFB),incorporating dispersing agents.The research employs a Central Composite Design from the Response SurfaceMethodology(RSM)with two factors:the type of dispersing agent(KCl and NaCl)and the NCC concentration fromOPEFB(1%-5%),along with the dispersing agent concentration(0.5%-3%).The objective of this study is to analyze the characteristics of food packaging bioplastics composed of a sago starch matrix,NCC from OPEFB,and dispersing agents.The novelty of this research lies in the development of food packaging bioplastics using sago starch reinforced withNCC fromOPEFB and the addition of dispersing agents(KCl andNaCl).The results indicate that incorporating NCC from OPEFB and dispersing agents significantly enhances the bioplastic’s properties,meeting the JIS 2-1707 standards for food packaging plastic films.The bioplastic was tested as packaging for gelamai(a traditional food from West Sumatra)through an organoleptic evaluation.Consumer acceptance in terms of taste,smell,and color remained satisfactory up to the 14th day.Further research is required to scale up production using the optimal formulation identified in this study.Additionally,this bioplastic is recommended for use as packaging for various food products.展开更多
We introduce a scheme aiming at the generation of quasi-monochromatic carbon ion bunches from laser-solid interaction.The proposed scheme is an extension of the“peeler”acceleration originally proposed for proton acc...We introduce a scheme aiming at the generation of quasi-monochromatic carbon ion bunches from laser-solid interaction.The proposed scheme is an extension of the“peeler”acceleration originally proposed for proton acceleration,which involves irradiating the narrow(submicrometer)side of a tape target.This results in the generation of a surface plasma wave and the subsequent acceleration of a proton bunch with high peak energy,quasi-monochromaticity,low energy bandwidth,and low divergence by the electrostatic field induced at the target rear.Up to now,the higher-Z(e.g.,carbon)ion bunches obtained with the peeler scheme have been found to exhibit an exponentially decaying thermal-like energy spectrum.To achieve a low energy bandwidth,we place a mass-limited carbon structure at the rear of the target.Using 3D particle-in-cell simulations,we show that a quasi-monochromatic carbon bunch can indeed be obtained.With a multi-PW laser pulse,10^(8) carbon ions with peak energy~110 MeV/u and with a divergence of 20° in the vertical plane and~1° in the horizontal plane can be generated.The quasi-monochromaticity,together with the low duration of the beam and in combination with the versatility of high-power laser facilities,should make this scheme attractive for practical applications such as heavy ion cancer therapy and higher-resolution diagnostics of extreme plasma states.展开更多
The utilization of oil palm biomass in the production of high-value products has increased substantially.Due to the presence of sugars and starches in their tissues,oil palms have an exceptionally low natural resistan...The utilization of oil palm biomass in the production of high-value products has increased substantially.Due to the presence of sugars and starches in their tissues,oil palms have an exceptionally low natural resistance to fungi,making them susceptible to contamination.In this study,the properties of particleboard made from oil palmfibers,namely empty fruit bunches(EFB),oil palm trunks(OPT),and oil palm fronds(OPF)fibers and its poten-tial for fungal attack were evaluated.The chemical composition,spectroscopic characterization,morphological features,and elemental analysis of oil palm biomassfibers were identified and thoroughly examined.The mechan-ical properties and dimensional stability of the boards were assessed based on Japanese Industrial Standards(JIS)and American National Standards Institute(ANSI)guidelines.The density,strength,and moisture resistance of particleboard made from OPTfibers may vary from those made from OPF and EFB due to inherent changes in chemical composition andfiber structure.These differences have an impact on the overall performance of the particleboard.Based on the ANOVA and Tukey’s test results,significant differences in elasticity properties were observed mainly between OPT and otherfibers,while bending strength revealed notable differences between various pairs of particleboards.The evaluation also highlighted variations in dimensional stability and water absorption capabilities.However,bending strength properties did not demonstrate any significant deviations.For the fungi test,fungal activity on the boards was observed over a two-week period in a controlled environment.The study revealed that oil palm-based particleboard exhibited susceptibility to fungal attacks,particularly from Aspergillus sp.,Trichoderma sp.,and Paecilomyces variotii.Thesefindings highlight the necessity for additional treatments to control or prevent fungal growth,thereby enhancing the commercial value of the particleboards.展开更多
The common phenomenon of uneven headway in bus service is explored based on the automatic vehicle location （AVL） data of Route 2 in Yichun City of Jiangxi province from 6：00 to 9：00 in the morning. The headway reg...The common phenomenon of uneven headway in bus service is explored based on the automatic vehicle location （AVL） data of Route 2 in Yichun City of Jiangxi province from 6：00 to 9：00 in the morning. The headway regularity of two stages 6： 00--7：00 and 7： 00--9：00 is comparatively analyzed, and it is found that both the traffic conditions and the passenger demand affect headway regularity. A bus arrival model, which assumes that the dwell time of a bus is linear in headway, is built to probe the effect of scheduled headway, and the model is simulated by Matlab. The simulation results reveal that the departure intervals and fluctuations affect headway regularity. Longer intervals and less fluctuation mean higher regularity of headway. And, the fluctuation has a more obvious influence on headway regularity than the interval. Controlling the fluctuations of scheduled headway can effectively raise the regularity of headway and improve the level of public transport service.展开更多
Effects of water-permeability plastic film plus bunch planting on root growth and development and yield of foxtail millet were studied by randomized block design. The results showed that water-permeability plastic fil...Effects of water-permeability plastic film plus bunch planting on root growth and development and yield of foxtail millet were studied by randomized block design. The results showed that water-permeability plastic film mulching plus bunch planting had a significant promoting effect on root growth and development and yield of foxtail millet. Compared with the CK, the total root length, total surface area, total root volume and number of. root tips increased by 51.30%, 47.89%, 48.39% and 41.63%, respectively. The yield increased by 48.57%, and there was significant positive correlation between root length, total surface area, total volume, number of root tips and dry matter weight of roots with yield. Developed roots are the main reason for the yield increasing effect of water-permeability plastic film mulching plus bunch planting.展开更多
To simulate the intense bunched beam transport, a computer program LEADS-3D has been developed. The particle trajectories are analysed with the Lie algebraic method. The third order approximation of the trajectory sol...To simulate the intense bunched beam transport, a computer program LEADS-3D has been developed. The particle trajectories are analysed with the Lie algebraic method. The third order approximation of the trajectory solutions is made with space charge forces off, and the second order approximation is made with space charge forces on. The particle distribution in the 3D ellipsoid is uniform or Gaussian. Most of the conventional beam optical elements are incorporated in the code. The optimization procedures are provided to fit the beam lines to satisfy the given optical conditions.展开更多
The adsorption capacity of activated carbon produced from oil palm empty fruit bunches through removal of 2,4-dichlorophenol from aqueous solution was carried out in the laboratory. The activated carbon was produced b...The adsorption capacity of activated carbon produced from oil palm empty fruit bunches through removal of 2,4-dichlorophenol from aqueous solution was carried out in the laboratory. The activated carbon was produced by thermal activation of activation time with 30 min at 800℃. The adsorption process conditions were determined with the statistical optimization followed by central composite design. A developed polynomial model for operating conditions of adsorption process indicated that the optimum conditions for maximum adsorption of phenolic compound were： agitation rate of 100 r/min, contact time of 8 h, initial adsorbate concentration of 250 mg/L and pH 4. Adsorption isotherms were conducted to evaluate biosorption process. Langmuir isotherm was more favorable （R^2=0.93） for removal of 2,4-dichlorophenol by the activated carbon rather than Freundlich isotherm （R^2=0.88）.展开更多
A technique of electron acceleration in the cone shaped stationary laser field is proposed. An electron acceleration in this laser is studied, which shows that there is no electron bunching but there exists electron c...A technique of electron acceleration in the cone shaped stationary laser field is proposed. An electron acceleration in this laser is studied, which shows that there is no electron bunching but there exists electron capture in this laser field.展开更多
This paper presents a method of generating terahertz （THz） coherent transition radiation （CTR） from picosecond ultrashort electron bunches including single and train bunches, which are produced by a photocathode r...This paper presents a method of generating terahertz （THz） coherent transition radiation （CTR） from picosecond ultrashort electron bunches including single and train bunches, which are produced by a photocathode radio frequency gun. The radiation characteristics of THz CTR including formation factor and energy spectrum are analysed in detail. With the help of a 2-dimensional particle-in-cell simulation, the radiation characteristics including power, energy and magnetic field are analysed. The results show that the radiation frequency can be adjusted by tuning the repetition frequency of the train bunch and the energy can be enhanced with the train bunches.展开更多
The feasibility of durian tree sawdust (DTS), coconut coir (CC) and oil palm empty fruit bunch (EFB) as low-cost biosorbents for the removal of Cu(II), Pb(II) and Zn(II) ions from aqueous solutions was investigated. T...The feasibility of durian tree sawdust (DTS), coconut coir (CC) and oil palm empty fruit bunch (EFB) as low-cost biosorbents for the removal of Cu(II), Pb(II) and Zn(II) ions from aqueous solutions was investigated. The effects of solution pH and initial metal concentration on adsorption capacity were examined in batch experiments. The affinity and the adsorption capacity of DTS, CC and EFB were evaluated. The adsorption behaviour of Cu(II), Pb(II) and Zn(II) ions onto DTS, CC and EFB was described using Freundlich and Langmuir isotherm models. The separation factor (RL) analysis suggests that the removal of metal ions onto three agricultural wastes studied was favourable. The maximum adsorption capacities (Q) estimated from the Langmuir isotherm model for Cu(II), Pb(II) and Zn(II) were 18.42, 20.37 and 22.78 mg/g for DTS, 18.38, 37.04 and 24.39 mg/g for CC, and 26.95, 37.59 and 21.19 mg/g for EFB, respectively. The characterisation studies were carried out using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX) and Fourier Transform Infrared Spectrometer (FTIR). The surface morphology of the biosorbents changed significantly following interaction with metal ions. The primary adsorption mechanism was complexation between metal ions and binding sites of biosorbents. Both hydroxyl and amine groups are the main binding sites in DTS, CC and EFB.展开更多
基金The project supported by the National Natural Science Foundation of China and the Science Foundation of Chinese Nuclear Industry
文摘The nonlinear space charge effect of a bunched beam with Gaussian distribu-tion in the longitudinal direction is discussed.Some useful formulae are derived for cal-culating the potential induced by a cylinder model of space charge in the waveguide of alinac with different combinations of density distribution:Gaussian distribution in thelongitudinal direction versus Kapchinskij Vladimirskij,waterbag,parabolic andGaussian distribution in the transverse direction,rcspectively.
文摘A novel bunched cerium oxide(CeO_(2))was prepared and its binary composite material with multi-walled carbon nanotubes presented an excellent microwave absorbing properties.The morphology,structure,and absorbing properties of the composite material were investigated.It was found that the minimum reflection loss(RL)of the composite material at 15.79 GHz was−45.7 dB when the thickness was 5.5 mm.It was worth noting that when the composite material was in the thickness range of 5.0-7.5 mm and the frequency was 11.36-17.77 GHz,the electromagnetic wave RL was<−30 dB,which illustrated that the composite material had a good absorbing effect over a wide thickness range.The results of the study contributed to the design and preparation of efficient microwave absorbing materials(MAM)with rare earth oxide composites and their applications,which demonstrated the importance of new composites with special structures in the field of MAM.
基金National Natural Science Foundation of China(12405168)The Fundamental Research Funds for the Central Universities,China(2024CDJXY004)。
文摘[Background]High harmonic cavities are widely used in electron storage rings to lengthen thebunch,lower the bunch peak current,thereby reducing the IBS effect,enhancing the Touschek lifetime,as well asproviding Landau damping,which is particularly important for storage rings operating with ultra-low emittance or atlow beam energy.[Purpose]To further increase the bunch length without additional hardware costs,the phasemodulation in a dual-RF system is considered.[Methods]In this paper,turn-by-turn simulations incorporating randomsynchrotron radiation excitation are conducted,and a brief analysis is presented to explain the bunch lengtheningmechanism.[Results]Simulation results reveal that the peak current can be further reduced,thereby mitigating IBSeffects and enhancing the Touschek lifetime.Although the energy spread increases,which tends to reduce thebrightness of higher-harmonic radiation from the undulator,the brightness of the fundamental harmonic can,in fact,beimproved.
基金supported by the Guangdong Basic and Applied Basic Research Foundation,China(No.2021B1515140007).
文摘The rapid cycling synchrotron(RCS)at the China spallation neutron source operates as a high-intensity proton accelerator.The coupled bunch instability was observed during RCS beam commissioning,which significantly limited the beam power.To investigate the dynamics of instability under an increased beam power,a pulsed octupole magnet with a gradient of 900 T/m^(3) was developed.The magnet system integrated an octupole magnet with a pulsed power supply.The field was carefully measured to examine the performance before its installation into the tunnel.After the installation of the magnets,beam measurements were performed to confirm the effectiveness of the instability mitigation on an actual proton beam.The measurement results show that the instability can be suppressed using the pulsed octupole magnet,particularly at the highenergy stage in an acceleration cycle,meeting the requirements for stable operation of the accelerator.Additionally,when the instability is completely suppressed through chromaticity optimization,octupole magnets can significantly enhance the RCS transmission efficiency,which is crucial for controlling beam loss.The pulsed octupole magnet offers significant progress in beam stability in the RCS,providing valuable experience for further beam power enhancement.
基金support from the NSRF via the Program Management Unit for Human Resources&Institutional Development,Research,and Innovation(No.B05F650022),as well as from Chiang Mai University.
文摘A super-radiant terahertz free-electron laser(THz-FEL)light source was developed for the first time in Thailand and Southeast Asia at the PBP-CMU Electron Linac Laboratory(PCELL)of Chiang Mai University.This radiation source requires relatively ultrashort electron bunches to produce intense coherent THz pulses.Three electron bunch compression processes are utilized in the PCELL accelerator system comprising pre-bunch compression in an alpha magnet,velocity bunching in a radio-frequency(RF)linear accelerator(linac),and magnetic bunch compression in a 180°acromat system.Electron bunch compression in the magnetic compressor system poses considerable challenges,which are addressed through the use of three quadrupole doublets.The strengths of the quadrupole fields significantly influence the rotation of the beam line longitudinal phase space distribution along the bunch compressor.Start-to-end beam dynamics simulations using the ASTRA code were performed to optimize the electron beam properties for generating super-radiant THz-FEL radiation.The operational parameters considered in the simulations comprise the alpha magnet gradient,linac RF phase,and quadrupole field strengths.The optimization results show that 10-16MeV femtosecond electron bunches with a low energy spread(~0.2%),small normalized emittance(~15πmm·mrad),and high peak current(165-247A)can be produced by the PCELL accelerator system at the optimal parameters.A THz-FEL with sub-microjoule pulse energies can thus be obtained at the optimized electron beam parameters.The physical and conceptual design of the THz-FEL beamline were completed based on the beam dynamics simulation results.The construction and installation of this beamline are currently underway and expected to be completed by mid-2024.The commissioning of the beamline will then commence.
文摘The use of organic fertilizers is less expensive and advantageous for both the development of the plant and the sanitation of the environment. This is why this investigation aims to promote the ash from emptying of oil mill boilers as a source of organic fertilization in the production of palm bunches. To do this, different doses of oil mill boiler emptying ash were tested on oil palms in production. The results showed that the oil palms responded favorably regardless of the dose of oil mill boiler emptying ash. Thus, the comparison of the different doses Tv1 (1 kg), Tv2 (1.5 kg), Tv3 (2 kg), Tv4 (3 kg), Tv5 (4 kg), Tv6 (5 kg) and Tv7 (7 kg) showed that the high doses led to an increase in the weight of the bunches. Better still, the Tv6 treatment at a dose of 5 kg/tree proved to be optimal for good production of palm bunches with a gain of 73.9% compared to the treatment without oil mill boiler emptying ash (absolute control).
基金the Government Collaboration Research Scheme of the TALENTA Grant of Universitas Sumatera Utara,No.41/UN5.2.3.1/PPM/KP-TALENTA/R/2023,29 August 2023.
文摘Activated charcoals were synthesized from sugar palm bunches(SPB)of the native tree of Arenga longipes in Indonesia.The synthesized activated charcoal(AC)was characterized,and utilized as an absorbent for heavy metals(lead/Pb and copper/Cu)through thermal activation.The synthesis of AC was accomplished through furnace activation at temperatures of 500℃,600℃,700℃,and 800℃.Acid chlorides were blended with the SPB-AC samples at 5%impregnation level and subsequently subjected to washing for activation,resulting in the elimination of volatile substances and ash content,which facilitates the development of a porous structure in the activated charcoal.The proximate analysis results indicated a reduction in weight and moisture content with an increase in activation temperature.The C-O,C=C,O-H stretching chains were not visible in the SPB-AC,indicating that the chains were broken after activation.The treatments at 600℃ and 700℃ exhibited superior thermal stability relative to the others.Moreover,there was a notable reduction in the signal strength of low-crystallinity amorphous carbon,indicating that the high-temperature treatment substantially altered the structural characteristics of the crystal.The SPB-AC produced at 700℃ exhibited a primarily microporous architecture,characterized by a maximal surface area,reduced total pore volume,and small particle size.In conclusion,elevating the activation temperature to 700℃ leads to notable improvement in the adsorption of Pb(91.61%)and Cu(95.19%)metals.
基金supported by the National Key Research and Development Program(No.2022YFC2402300)。
文摘Industrial linear accelerators often contain many bunches when their pulse widths are extended to microseconds.As they typically operate at low electron energies and high currents,the interactions among bunches cannot be neglected.In this study,an algorithm is introduced for calculating the space charge force of a train with infinite bunches.By utilizing the ring charge model and the particle-in-cell(PIC)method and combining analytical and numerical methods,the proposed algorithm efficiently calculates the space charge force of infinite bunches,enabling the accurate design of accelerator parameters and a comprehensive understanding of the space charge force.This is a significant improvement on existing simulation software such as ASTRA and PARMELA that can only handle a single bunch or a small number of bunches.The PIC algorithm is validated in long drift space transport by comparing it with existing models,such as the infinite-bunch,ASTRA single-bunch,and PARMELA several-bunch algorithms.The space charge force calculation results for the external acceleration field are also verified.The reliability of the proposed algorithm provides a foundation for the design and optimization of industrial accelerators.
基金funded by the Regular Fundamental Research Grant of the Directorate of Research,Technology,and Community Service,Ministry of Education,Culture,Research,and Technology,Republic of Indonesia No.093/E5/PG.02.00.PL/2024Research Institution of Universitas Sumatera Utara No.1/UN5.4.10S/PPM/KPDRTPM/2024supported by the project“Development,Exploitation Properties and Application of Eco-Friendly Wood-Based Composites from Alternative Lignocellulosic Raw Materials”,Project No.HN C--1290/19.10.2023,carried out at the University of Forestry,Sofia,Bulgaria.
文摘The utilisation of sugar palm bunches-charcoal briquettes(SPB-CB)represents a significant advancement in biomass energy.This study aimed to analyse the properties of charcoal briquettes produced from SPB(Arenga longipes).The experiment involved categorising the dimensions of charcoal powder into three specific particle sizes:20-40 mesh,40-60 mesh,and particles that could pass through a 60-mesh screen.The charcoal powder will be combined with tapioca as a binding agent at three specific concentrations:11%,13%,and 15%.The research findings indicate that the samples underwent 60 mesh passes achieved the maximum briquette density,with an average value of 0.58 g/cm^(3).The highest attainable compressive strength sample value was 27.52 kgf/cm^(2),which was attained by employing 60 mesh size and 15%adhesive concentration.The calorimetric investigation showed that SPB-charcoal had the highest calorific value of 25.88 MJ/kg,while the SPB-CB had a little lower caloric value of 24.64 MJ/kg.The ash content and volatile matter values showed that the briquettes with the lowest ash content had values of 10.49%and 32.65%,respectively.Furthermore,the carbon fixation values varied between 16.65%and 52.36%.Thermogravimetric analysis indicates that charcoal derived from SPB exhibits superior thermal characteristics compared to charcoal briquettes.However,thermal properties of SPB charcoal do not show significant differences when compared to charcoal briquettes that have been processed with a mesh size of 20-40 and include 11%adhesive.According to this research,it may be inferred that charcoal briquettes made from sugar palm bunches meet the requirements specified in SNI 01-6235-2000.
基金the Industrial Human Resource Development Agency,Ministry of Industry in 2023。
文摘The development of the bioplastics industry addresses critical issues such as environmental pollution and food safety concerns.However,the industrialization of bioplastics remains underdeveloped due to challenges such as high production costs and suboptimal material characteristics.To enhance these characteristics,this study investigates bioplastics reinforced with Nanocrystalline Cellulose(NCC)derived from Oil Palm Empty Fruit Bunches(OPEFB),incorporating dispersing agents.The research employs a Central Composite Design from the Response SurfaceMethodology(RSM)with two factors:the type of dispersing agent(KCl and NaCl)and the NCC concentration fromOPEFB(1%-5%),along with the dispersing agent concentration(0.5%-3%).The objective of this study is to analyze the characteristics of food packaging bioplastics composed of a sago starch matrix,NCC from OPEFB,and dispersing agents.The novelty of this research lies in the development of food packaging bioplastics using sago starch reinforced withNCC fromOPEFB and the addition of dispersing agents(KCl andNaCl).The results indicate that incorporating NCC from OPEFB and dispersing agents significantly enhances the bioplastic’s properties,meeting the JIS 2-1707 standards for food packaging plastic films.The bioplastic was tested as packaging for gelamai(a traditional food from West Sumatra)through an organoleptic evaluation.Consumer acceptance in terms of taste,smell,and color remained satisfactory up to the 14th day.Further research is required to scale up production using the optimal formulation identified in this study.Additionally,this bioplastic is recommended for use as packaging for various food products.
基金the support of the Romanian Government and the European Union through the European Regional Development Fund–the Competitiveness Operational Programme (1/07.07.2016, COP, Grant ID No. 1334) Phases Ⅱthe Romanian Ministry of Research, Innovation and Digitalization: Program Nucleu Grant No. PN23210105+6 种基金supported by the IOSIN Funds for Research Infrastructures of National Interest funded by the Romanian Ministry of Research, Innovation and Digitalizationsupported by Project No. ELI-RO/DFG/2023_001 ARNPhot funded by the Institute of Atomic Physics (Romania), the European Union, the Romanian Governmentthe Health Program, within the project “Medical Applications of High-Power Lasers–Dr. LASER,” SMIS Code 326475by Grant Nos. ELI-RO/RDI/2024_14 SPARC and ELI-RO/RDI/2024_8 AMAPBMBF Grant No. 05P24PF2 (Germany)the EuroHPC Joint Undertaking for awarding us access to Karolina at IT4Innovations (VAB-TU), Czechia under Project No. EHPCREG-2023R02-006 (Grant No. DD-23-157)Ministry of Education, Youth and Sports of the Czech Republic through e-INFRA CZ (Grant ID No. 90140)
文摘We introduce a scheme aiming at the generation of quasi-monochromatic carbon ion bunches from laser-solid interaction.The proposed scheme is an extension of the“peeler”acceleration originally proposed for proton acceleration,which involves irradiating the narrow(submicrometer)side of a tape target.This results in the generation of a surface plasma wave and the subsequent acceleration of a proton bunch with high peak energy,quasi-monochromaticity,low energy bandwidth,and low divergence by the electrostatic field induced at the target rear.Up to now,the higher-Z(e.g.,carbon)ion bunches obtained with the peeler scheme have been found to exhibit an exponentially decaying thermal-like energy spectrum.To achieve a low energy bandwidth,we place a mass-limited carbon structure at the rear of the target.Using 3D particle-in-cell simulations,we show that a quasi-monochromatic carbon bunch can indeed be obtained.With a multi-PW laser pulse,10^(8) carbon ions with peak energy~110 MeV/u and with a divergence of 20° in the vertical plane and~1° in the horizontal plane can be generated.The quasi-monochromaticity,together with the low duration of the beam and in combination with the versatility of high-power laser facilities,should make this scheme attractive for practical applications such as heavy ion cancer therapy and higher-resolution diagnostics of extreme plasma states.
文摘The utilization of oil palm biomass in the production of high-value products has increased substantially.Due to the presence of sugars and starches in their tissues,oil palms have an exceptionally low natural resistance to fungi,making them susceptible to contamination.In this study,the properties of particleboard made from oil palmfibers,namely empty fruit bunches(EFB),oil palm trunks(OPT),and oil palm fronds(OPF)fibers and its poten-tial for fungal attack were evaluated.The chemical composition,spectroscopic characterization,morphological features,and elemental analysis of oil palm biomassfibers were identified and thoroughly examined.The mechan-ical properties and dimensional stability of the boards were assessed based on Japanese Industrial Standards(JIS)and American National Standards Institute(ANSI)guidelines.The density,strength,and moisture resistance of particleboard made from OPTfibers may vary from those made from OPF and EFB due to inherent changes in chemical composition andfiber structure.These differences have an impact on the overall performance of the particleboard.Based on the ANOVA and Tukey’s test results,significant differences in elasticity properties were observed mainly between OPT and otherfibers,while bending strength revealed notable differences between various pairs of particleboards.The evaluation also highlighted variations in dimensional stability and water absorption capabilities.However,bending strength properties did not demonstrate any significant deviations.For the fungi test,fungal activity on the boards was observed over a two-week period in a controlled environment.The study revealed that oil palm-based particleboard exhibited susceptibility to fungal attacks,particularly from Aspergillus sp.,Trichoderma sp.,and Paecilomyces variotii.Thesefindings highlight the necessity for additional treatments to control or prevent fungal growth,thereby enhancing the commercial value of the particleboards.
基金The National Basic Research Program of China(973 Program)(No.2012CB725402)the National Natural Science Foundation of China(No.50978057)Program of Scientific Innovation Research of College Graduate in Jiangsu Province(No.CXLX12_0108)
文摘The common phenomenon of uneven headway in bus service is explored based on the automatic vehicle location （AVL） data of Route 2 in Yichun City of Jiangxi province from 6：00 to 9：00 in the morning. The headway regularity of two stages 6： 00--7：00 and 7： 00--9：00 is comparatively analyzed, and it is found that both the traffic conditions and the passenger demand affect headway regularity. A bus arrival model, which assumes that the dwell time of a bus is linear in headway, is built to probe the effect of scheduled headway, and the model is simulated by Matlab. The simulation results reveal that the departure intervals and fluctuations affect headway regularity. Longer intervals and less fluctuation mean higher regularity of headway. And, the fluctuation has a more obvious influence on headway regularity than the interval. Controlling the fluctuations of scheduled headway can effectively raise the regularity of headway and improve the level of public transport service.
文摘Effects of water-permeability plastic film plus bunch planting on root growth and development and yield of foxtail millet were studied by randomized block design. The results showed that water-permeability plastic film mulching plus bunch planting had a significant promoting effect on root growth and development and yield of foxtail millet. Compared with the CK, the total root length, total surface area, total root volume and number of. root tips increased by 51.30%, 47.89%, 48.39% and 41.63%, respectively. The yield increased by 48.57%, and there was significant positive correlation between root length, total surface area, total volume, number of root tips and dry matter weight of roots with yield. Developed roots are the main reason for the yield increasing effect of water-permeability plastic film mulching plus bunch planting.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10975011)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20070001001)
文摘To simulate the intense bunched beam transport, a computer program LEADS-3D has been developed. The particle trajectories are analysed with the Lie algebraic method. The third order approximation of the trajectory solutions is made with space charge forces off, and the second order approximation is made with space charge forces on. The particle distribution in the 3D ellipsoid is uniform or Gaussian. Most of the conventional beam optical elements are incorporated in the code. The optimization procedures are provided to fit the beam lines to satisfy the given optical conditions.
文摘The adsorption capacity of activated carbon produced from oil palm empty fruit bunches through removal of 2,4-dichlorophenol from aqueous solution was carried out in the laboratory. The activated carbon was produced by thermal activation of activation time with 30 min at 800℃. The adsorption process conditions were determined with the statistical optimization followed by central composite design. A developed polynomial model for operating conditions of adsorption process indicated that the optimum conditions for maximum adsorption of phenolic compound were： agitation rate of 100 r/min, contact time of 8 h, initial adsorbate concentration of 250 mg/L and pH 4. Adsorption isotherms were conducted to evaluate biosorption process. Langmuir isotherm was more favorable （R^2=0.93） for removal of 2,4-dichlorophenol by the activated carbon rather than Freundlich isotherm （R^2=0.88）.
文摘A technique of electron acceleration in the cone shaped stationary laser field is proposed. An electron acceleration in this laser is studied, which shows that there is no electron bunching but there exists electron capture in this laser field.
基金Project supported by the Key Program of National Natural Science Foundation of China (Grant No.10705050)National Natural Science Foundation of China (Grant Nos.10875070,10805031,and 10905032)+1 种基金China Postdoctoral Science Foundation (Grant No.20080440031)China Postdoctoral Special Science Foundation (Grant No.200902088)
文摘This paper presents a method of generating terahertz （THz） coherent transition radiation （CTR） from picosecond ultrashort electron bunches including single and train bunches, which are produced by a photocathode radio frequency gun. The radiation characteristics of THz CTR including formation factor and energy spectrum are analysed in detail. With the help of a 2-dimensional particle-in-cell simulation, the radiation characteristics including power, energy and magnetic field are analysed. The results show that the radiation frequency can be adjusted by tuning the repetition frequency of the train bunch and the energy can be enhanced with the train bunches.
文摘The feasibility of durian tree sawdust (DTS), coconut coir (CC) and oil palm empty fruit bunch (EFB) as low-cost biosorbents for the removal of Cu(II), Pb(II) and Zn(II) ions from aqueous solutions was investigated. The effects of solution pH and initial metal concentration on adsorption capacity were examined in batch experiments. The affinity and the adsorption capacity of DTS, CC and EFB were evaluated. The adsorption behaviour of Cu(II), Pb(II) and Zn(II) ions onto DTS, CC and EFB was described using Freundlich and Langmuir isotherm models. The separation factor (RL) analysis suggests that the removal of metal ions onto three agricultural wastes studied was favourable. The maximum adsorption capacities (Q) estimated from the Langmuir isotherm model for Cu(II), Pb(II) and Zn(II) were 18.42, 20.37 and 22.78 mg/g for DTS, 18.38, 37.04 and 24.39 mg/g for CC, and 26.95, 37.59 and 21.19 mg/g for EFB, respectively. The characterisation studies were carried out using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX) and Fourier Transform Infrared Spectrometer (FTIR). The surface morphology of the biosorbents changed significantly following interaction with metal ions. The primary adsorption mechanism was complexation between metal ions and binding sites of biosorbents. Both hydroxyl and amine groups are the main binding sites in DTS, CC and EFB.
