The underwater tapping machine is composed of a center bit, a tapping cutter, a seal box, a main drive box, a boring bar assembly, a envelop, a gear case, a counter and so on. The drive system in underwater tapping ma...The underwater tapping machine is composed of a center bit, a tapping cutter, a seal box, a main drive box, a boring bar assembly, a envelop, a gear case, a counter and so on. The drive system in underwater tapping machine consists of a worm drive, a gear drive system and a screw drive. The worm drive is in the main drive box. The worm is connected with a hydraulic motor and driven by the hydraulic motor. The gear drive system is a combined gear train which is the combinations of the fixed axes and differential gear train in the gear case. On the one hand, by means of the fixed axes gear trains the turn and power of transmission shaft are transferred to the boring bar and the screw rod, causing differential turn between the boring bar and the screw rod. On the other hand, the turns of the boring bar and the screw rod are transferred to the differential gear train. The differential gear train is used to drive a special counter to count axial travel of the boring bar. The screw drive is composed of a feed screw and a nut on the boring bar. There is the differential turn between the boring bar and the feed screw. By means of the nut, the boring bar can feed automatically. With the movement of the sliding gear 7 in the gear case, the designed drive system can also be provided with the ability of fast forward and fast backward movement of the boring bar in its idle motion, resulting in the increase of the tapping efficiency.展开更多
The engineblock production lines need high speed tapping with tungsten carbide taps. In the tapping process, the machining precision and the tool life of taps are directly influenced by tapping forces. And the paramet...The engineblock production lines need high speed tapping with tungsten carbide taps. In the tapping process, the machining precision and the tool life of taps are directly influenced by tapping forces. And the parameter optimization of tap structures is also correlated with the variation of tapping forces. Therefore, the study of tapping forces is necessary in developing new style taps. Several experiments about some novel carbide taps are performed on a vertical machining center by a Kistler dynamometer system in blind tapping both gray cast iron and ductile cast iron. And the variations of tapping forces are analyzed in tapping-in and tapping-out periods. It indicates that cutting forces hardly vary with the tap wear in tapping cast iron. Contrarily, tapping forces are closely correlated with the holding method. Besides, it also depends on the helix angle, the flute numbers and the plasticity of the work material to some extent.展开更多
Objective To observe the clinical effect on cervical spondylosis of nerve root type treated by warm needling therapy at Jiáj （夹脊 EX-B 2） and plum-blossom needle therapy. Methods According to the random number...Objective To observe the clinical effect on cervical spondylosis of nerve root type treated by warm needling therapy at Jiáj （夹脊 EX-B 2） and plum-blossom needle therapy. Methods According to the random number table, 150 cases of cervical spondylosis of nerve root type were randomized into an acupuncture-moxibustion group （75 cases） and a control group （75 cases）. In the acupuncture-moxibustion group, the warm needling at EX-B 2 and tapping with plum-blossom needle were applied. EX-B 2 on the affected segments were selected and stimulated with warm needling technique for 20– 30 min. Afterward, the plum-blossom needle was used to tap the skin around the acupoints, for 3 min on each site. The treatment was given once every day. Seven treatments made one session. The interval between two sessions was 1 day. In the control group, the medication was used in combination with traction therapy. The intravenous drip with 5% glucose 250 mL and compound salvia miltiorrhiza injection 40 mL was used, once a day. In traction treatment, the patient was in a sitting position, neck anteflexion at 15°–30°, traction force at 10%–20% of the body mass, for 20–30 min in each time. The treatment was given once every day. The appointed person evaluated therapeutic effects after the three sessions of treatment in the two groups. Results The clinical curative rate was 49.3% （37/75） and the total effective rate was 94.7% （71/75） in the acupuncture-moxibustion group and those were 24.0% （18/75） and 81.3% （61/75） respectively in the control group. The total effective rate and clinical curative rate in the acupuncture-moxibustion group were superior to the control group （both P0.05）. In the comparison of the duration of treatment and effect in the cured patients between the two groups, the curative rate in the 1st session of treatment in the acupuncture-moxibustion group was higher than that in the control group （P0.05）. In the comparison of the 6-month follow-up visit in the cured patients between the two groups, the effect in the acupuncture-moxibustion group was much more stable （P0.05）. Conclusion The warm needling therapy at EX-B 2 and tapping therapy with plum-blossom needle achieve the significant effect on cervical spondylosis of nerve root type.展开更多
Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utili...Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utilizing the reactive power capability of PV inverters to mitigate voltage deviations is being promoted.In recent years,droop control of inverter-based distributed energy resources has emerged as an essential tool for use in this study.The participation of PV systems in voltage regulation and its coordination with existing controllers,such as on-load tap changers,is paramount for controlling the voltage within specified limits.In this work,control strategies are presented that can be coordinated with the existing controls in a distributed manner.The effectiveness of the proposed method was demonstrated through simulation results on a distribution system.展开更多
The fifth generation （5G） wireless communication is currently a hot research topic and wireless communication systems on high speed railways （HSR） are important applications of 5G technologies. Existing stud- ies ...The fifth generation （5G） wireless communication is currently a hot research topic and wireless communication systems on high speed railways （HSR） are important applications of 5G technologies. Existing stud- ies about 5G wireless systems on high speed railways （HSR） often utilize ideal channel parameters and are usually based on simple scenarios. In this paper, we evaluate the down- link throughput of 5G HSR communication systems on three typical scenarios including urban, cutting and viaduct with three different channel estimators. The channel parameters of each scenario are generated with tapped delay line （TDL） models through ray-tracing sim- ulations, which can be considered as a good match to practical situations. The channel estimators including least square （LS）, linear minimum mean square error （LMMSE）, and our proposed historical information based ba- sis expansion model （HiBEM）. We analyze the performance of the HiBEM estimator in terms of mean square error （MSE） and evaluate the system throughputs with different channel estimates over each scenario. Simulation results are then provided to corroborate our proposed studies. It is shown that our HiBEM estimator outperforms other estimators and that the sys-tem throughput can reach the highest point in the viaduct scenario.展开更多
A machine vision for assessing and inspecting the ratio of thread areas associated with fixed frequency (FF) and limited tracing frequency (LTF) ultrasonic-assisted vibration was presented using differently coated tap...A machine vision for assessing and inspecting the ratio of thread areas associated with fixed frequency (FF) and limited tracing frequency (LTF) ultrasonic-assisted vibration was presented using differently coated taps after tapping of Ti-6Al-4V alloys.Experimental results indicate that TiAlN Micran taps yield the best tapping quality for different coatings and tapping conditions.TiAlN Micran coated taps with LTF make the largest improvement over traditional tapping (TT),with an average increase of 30.2%.展开更多
Acacia senegal, the gum arabic producing tree, is the most important tree species for the livelihood of the people in South Kordofan State, Sudan. The objective of this study was to determine the optimum tapping date ...Acacia senegal, the gum arabic producing tree, is the most important tree species for the livelihood of the people in South Kordofan State, Sudan. The objective of this study was to determine the optimum tapping date for gum arabic production in the study area. A randomized complete block design experiment with three replications was conducted at （Mead） area for two continuous growing seasons 2008/2009 - 2009/2010. The treatments comprised six tapping dates （1 Oct, 15 Oct, 1 Nov, 15 Nov, 1 Dec, and 15 Dec）. Results ishowed highly significant differences （p 〈 0.001） in gum arabic yield （g／tree） in all pickings and in the total gum yield between the tapping dates. The results also showed that tapping of trees on 15 October and 1 November gave a higher yield compared to the other dates. The highest gum yield of 1086.6 and 661.2 g/tree was recorded on 15 October and 15 November, while the lowest gum yield of 297.9 g/tree was recorded when the trees were tapped on 1 October. The two highest-yield dates of tapping （15 Oct and 1 Nov） are recommended as the best time for tapping for gum arabic production in South Kordofan State. These results can be used to increase gum arabic production and farmer income in South Kordofan State.展开更多
The thermal conductivities of different typical species filling materials for sliding gate systems for steel ladles were measured using a hot wire technique, and the relationships between thermal conductivity and te...The thermal conductivities of different typical species filling materials for sliding gate systems for steel ladles were measured using a hot wire technique, and the relationships between thermal conductivity and temperature were regressed. The factors affecting thermal conductivity were analyzed by using variance analysis for a perpendicular experiment. The effects of thermal conductivity on sliding gate free tapping were studied, and it was revealed that decreasing the thermal conductivity of the filling materials is beneficial in enhancing the rate of free tapping for sliding gates.展开更多
Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current(DC)power adjustment.Based on a converter steady-state model and a DC power model,the control angle constraints ...Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current(DC)power adjustment.Based on a converter steady-state model and a DC power model,the control angle constraints of a converter valve are relaxed for power regulation.In this paper,a flexible DC power control method based on a fixed tap changer position is proposed.The initial ratio of the converter transformer is optimized.The effects of the fixed-tap changer position control on the control angle,reactive power compensation,and commutation failure are analyzed.The new control method allows a DC system to operate at a large angle and increase the additional reactive power loss while improving the commutation security margin.Steady-state and electromagnetic transient simulations in the CIGRE test system verify the validity of the method proposed in this paper and the correctness of the analysis conclusions.展开更多
Industrial applications of natural gums have been expanding tremendously, so gum collection from trees provides an important livelihood for local dwellers in drought-prone Rajasthan and its surroundings states. Tradit...Industrial applications of natural gums have been expanding tremendously, so gum collection from trees provides an important livelihood for local dwellers in drought-prone Rajasthan and its surroundings states. Traditional gum tapping is crude and unscientific; deep incision, untimely extraction and high concentration of chemicals in gum have affected Sterculia urens species in its natural habitat. In studies 2 years on trees having diameter at breast height 〉40 cm from natural stands to maximize gum collection and standardize the tapping method （bore holes vs. V blazes）, tapping season, chemical and concentration, different tapping techniques were tes- ted. For tapping maximum gum was collected using bore hole. Ethephon was better as extraction chemical than sulphuric acid. Bore-hole tapping with a 5-cm hole and ethephon at 300 mg/mL yielded the most gum （135.20 g/ tree）. Ethephon at 300 mg/mL yielded the most gum. Ethephon induced gummosis without affecting the health of tree. Tapping seasons also significantly affected the gum yield; the most gum was obtained in April-June.展开更多
The periodic impact force induced by tip-sample contact in a tapping mode atomic force microscope （AFM） gives rise to the non-harmonic response of a micro-cantilever. These non-harmonic signals contain the full char...The periodic impact force induced by tip-sample contact in a tapping mode atomic force microscope （AFM） gives rise to the non-harmonic response of a micro-cantilever. These non-harmonic signals contain the full characteristics of tip-sample interaction. A complete theoretical model describing the dynamical behaviour of tip-sample system was developed in this paper. An analytic formula was introduced to describe the relationship between time-varying tip-sample impact force and tip motion. The theoretical analysis and numerical results both show that the timevarying tip-sample impact force can be reconstructed by recording tip motion. This allows for the reconstruction of the characteristics of the tip-sample force, like contact time and maximum contact force. It can also explain the ability of AFM higher harmonics imaging in mapping stiffness and surface energy variations.展开更多
A technique using artificial neural networks trained with parameters derived from delay tap plots for optical performance monitoring in 40 Gbit/s duobinary system is demonstrated. Firstly, the optical signal is delay ...A technique using artificial neural networks trained with parameters derived from delay tap plots for optical performance monitoring in 40 Gbit/s duobinary system is demonstrated. Firstly, the optical signal is delay tap sampled to obtain two-dimensional histogram, known as delay tap plots. Secondly, the features of delay tap plots are extracted to train the feed forward, three-layer preceptor structure artificial neural networks. Finally, the outputs of trained neural network are used to monitor optical duobinary signal impairments. Simulation of optical signal noise ratio （ OSNR）, chromatic dispersion （CD）, and differential group delay （DGD） monitoring in 40 Gbit/s optical duo- binary system is presented. The proposed monitoring scheme can accurately identify simultaneous impairments without requiring synchronous sampling or data clock recovery. The proposed technique is simple, cost-effective and suitable for in-service distributed OPM.展开更多
The rubber tree Hevea brasiliensis(Willd.Ex Adr.De Juss.)Müell Arg.]is an important source of latex for the production natural rubber.Natural rubber is an important biopolymer used in various industries,but aspec...The rubber tree Hevea brasiliensis(Willd.Ex Adr.De Juss.)Müell Arg.]is an important source of latex for the production natural rubber.Natural rubber is an important biopolymer used in various industries,but aspects related to hormonal regulation in biosynthesis are still unknown,which would allow optimizing its production.We review the molecular and physiological mechanisms of increases latex regeneration and flow by the stimulation of rubber trees with exogenous applications of ethylene and jasmonate.We found that the increase in latex regeneration by ethylene is due to the increase in gene level expression and enzymatic activity of key photosynthesis and glycolysis enzymes for the generation of precursors in the first phase of rubber biosynthesis.Latex flow is supported by up-regulated genes in sucrose metabolism such as invertases,induction of sucrose transporters(SUT),and aquaporins(PIP)to maintain flow and turgor pressure in laticifers.Meanwhile,the increase in latex yield mediated by jasmonate may be due to the induction of laticifer differentiation in the long term and in the short term be mediated by the induction of small rubber particles(SRPP)as non-enzymatic cofactors in the production of latex.This information contributes to the knowledge of latex biosynthesis,which allows for a greater support for the exogenous application of jasmonates and ethylene to regulate its production.展开更多
A study was conducted in South Kordofan, Sudan to determine the effect of tapping, tapping tools and date of tapping on the gum yield of Acacia polyacantha. A two-factor experiment was conducted for two seasons in 200...A study was conducted in South Kordofan, Sudan to determine the effect of tapping, tapping tools and date of tapping on the gum yield of Acacia polyacantha. A two-factor experiment was conducted for two seasons in 2008-2009. One location was used for two seasons and two locations for one season. The first factor （4 levels） was the tools of tapping： Makmak, Farrar, and Sonki, and the control which was not tapped. The second factor （2 levels） was the date of tapping that comprises mid October and mid November. These treatments were arranged in Randomaized Complete Block Design and replicated three times. Gum yield （g/tree and g/ picking） was recorded for five pickings. Economic analysis was done using the partial budget technique. The results showed highly significant （p 〈 0.01） differences on gum yield （g/picking and g/tree）. The results indicated that the process of tapping increases gum production by 88.4% and 79.8% compared with un-tapped trees, respectively. The date of tapping has no significant effect on gum yield （g/tree and g/picking） of A. polyacantha. Tapping of the tree with Makmak in mid- November was found to be economically beneficial compared to using the other tools and the control. These results could identify a new source of income for the poor farmers in South Kordofan mainly because of the wild occurrence of Kakamut as a potential gum producing tree species grown naturally in the area.展开更多
We conducted a two-factor experiment in randomized complete block design with four replications during 2004 in El Demokeya Forest Reserve and El Himaira Natural Forest, North Kordofan State, Sudan. The objective was t...We conducted a two-factor experiment in randomized complete block design with four replications during 2004 in El Demokeya Forest Reserve and El Himaira Natural Forest, North Kordofan State, Sudan. The objective was to develop an understanding of the ecological effects of under-story vegetation and tapping date on the productivity of gum arabic from Acacia senegal as over story cover. The first factor was grass cover which was tested in four levels （100% and 50% grass cover in addition to bare and burnt）. The second factor, date of tapping was tested in three levels namely （1st Oct, 15th Oct and 1st Nov）. The first picking was done after 45 days from tapping and the gum yield up to seven pickings was collected at intervals of 15 days. Gum yield from each picking was collected and weighed using sensitive balance. Analysis of variance was carried out using MSTAT-C statistical package, and the Tukey test was applied for mean comparisons. The results showed highly significant differences （p 〈 0.01） of grass cover on gum arabic yield in the two sites for most of the first consecutive pickings （1st–4th out of seven） in addition to total yield （kg/ha）. With exception to the 4th pickings, the interaction effect between the grass densities and tapping date was not significantly different. The total gum yield was significantly （p 〈 0.05） increased in only two pickings （third and fourth） in El Demokeya Forest Reserve and two pickings （1st and 2nd） at El Himaira Natural Forest. The density of grass cover significantly （p 〈 0.05） affected the number of pickings at both sites; the number of gum pickings was directly proportional to grass density. The number of gum pickings was found to be significantly （p 〈 0.05） increased at the early date of tapping.展开更多
An integrated Plate Mill has started it’s operation on July 7, 2010 in Gwangyang Steelworks, POSCO. The production capability is about 2.5 million tons per year and the main stream consists of Blast Furnace, Hot meta...An integrated Plate Mill has started it’s operation on July 7, 2010 in Gwangyang Steelworks, POSCO. The production capability is about 2.5 million tons per year and the main stream consists of Blast Furnace, Hot metal pretreatment (KR), Converter, Bubbling Station, RH/VTD and Continuous Casting. Particularly, it is possible to control sulfur concentration at excellent level in BOF without any further treatment in LF or VTD, which is attained by unique KR process and scrap usage strategy in BOF. In this paper, desulfurization efficiency and steel cleanliness was introduced by optimizing flux amount during tapping in BOF process. In addition, the effect of the flux addition on the refractory of ladle was investigated based on EPMA analyses with the viewpoint of phase diagram. The cleanliness of each sample was examined using optical emission spectrometry and oxygen nitrogen determinator.展开更多
Slash pine(Pinus elliottii Engelm.var.elliottii)is a resin-producing species grown worldwide for significant economic benefits for wood production.Resin tapping cre-ates a carbon sink at the expense of carbon allocati...Slash pine(Pinus elliottii Engelm.var.elliottii)is a resin-producing species grown worldwide for significant economic benefits for wood production.Resin tapping cre-ates a carbon sink at the expense of carbon allocation for growth and consequently,wood production may be reduced.Non-structural carbohydrates comprising starch and sugars stored in plant organs,may serve as intermediate pools between assimilation and utilisation.However,the effect of resin tapping between tree growth and non-structural carbo-hydrates is not well understood.This study investigated(1)the effects of resin tapping on radial growth,(2)the effects of resin tapping on non-structural carbohydrate pools in different compartments,and(3)the feasibility of resin pro-duction without disruption of tree growth.Twenty one-year-old slash pines were subjected to resin tapping over two suc-cessive years.Non-structural carbohydrate concentrations in needles,branches,stem phloem,and roots of tapped and untapped trees in summer and winter were determined after the second year of resin harvest.The results showed that tapping had no significant effects on annual increments.Starch was the dominant non-structural carbohydrate frac-tion,regardless of tissues and season,and constituted up to 99%of the total non-structural carbohydrates in the phloem and roots.Glucose and fructose were the dominant sugars;sucrose was negligible.Compared with the controls,tapped trees showed 26%lower non-structural carbohydrate concen-tration in the phloem above the tapping wound in summer,which was attributable to the decreased abundance of starch,glucose,fructose,and sucrose.In winter,the altered non-structural carbohydrate profiles in the phloem above the tap-ping wounding were minimised as a result of recovery of the sugar concentrations.In contrast to free sugars,which accu-mulated substantially in needles and branches during winter,starch was enriched in the phloem,roots,and current-year needles.The results provide evidence for a localised effect of resin tapping,and highlight the observation that resin extrac-tion does not always cause a sacrifice in wood growth under a moderate resin-tapping intensity in slash pine plantations.展开更多
基金supported by the National High Technology Research and Development Program of China(863 Program, Grant No.2002AA602012-2)
文摘The underwater tapping machine is composed of a center bit, a tapping cutter, a seal box, a main drive box, a boring bar assembly, a envelop, a gear case, a counter and so on. The drive system in underwater tapping machine consists of a worm drive, a gear drive system and a screw drive. The worm drive is in the main drive box. The worm is connected with a hydraulic motor and driven by the hydraulic motor. The gear drive system is a combined gear train which is the combinations of the fixed axes and differential gear train in the gear case. On the one hand, by means of the fixed axes gear trains the turn and power of transmission shaft are transferred to the boring bar and the screw rod, causing differential turn between the boring bar and the screw rod. On the other hand, the turns of the boring bar and the screw rod are transferred to the differential gear train. The differential gear train is used to drive a special counter to count axial travel of the boring bar. The screw drive is composed of a feed screw and a nut on the boring bar. There is the differential turn between the boring bar and the feed screw. By means of the nut, the boring bar can feed automatically. With the movement of the sliding gear 7 in the gear case, the designed drive system can also be provided with the ability of fast forward and fast backward movement of the boring bar in its idle motion, resulting in the increase of the tapping efficiency.
文摘The engineblock production lines need high speed tapping with tungsten carbide taps. In the tapping process, the machining precision and the tool life of taps are directly influenced by tapping forces. And the parameter optimization of tap structures is also correlated with the variation of tapping forces. Therefore, the study of tapping forces is necessary in developing new style taps. Several experiments about some novel carbide taps are performed on a vertical machining center by a Kistler dynamometer system in blind tapping both gray cast iron and ductile cast iron. And the variations of tapping forces are analyzed in tapping-in and tapping-out periods. It indicates that cutting forces hardly vary with the tap wear in tapping cast iron. Contrarily, tapping forces are closely correlated with the holding method. Besides, it also depends on the helix angle, the flute numbers and the plasticity of the work material to some extent.
文摘Objective To observe the clinical effect on cervical spondylosis of nerve root type treated by warm needling therapy at Jiáj （夹脊 EX-B 2） and plum-blossom needle therapy. Methods According to the random number table, 150 cases of cervical spondylosis of nerve root type were randomized into an acupuncture-moxibustion group （75 cases） and a control group （75 cases）. In the acupuncture-moxibustion group, the warm needling at EX-B 2 and tapping with plum-blossom needle were applied. EX-B 2 on the affected segments were selected and stimulated with warm needling technique for 20– 30 min. Afterward, the plum-blossom needle was used to tap the skin around the acupoints, for 3 min on each site. The treatment was given once every day. Seven treatments made one session. The interval between two sessions was 1 day. In the control group, the medication was used in combination with traction therapy. The intravenous drip with 5% glucose 250 mL and compound salvia miltiorrhiza injection 40 mL was used, once a day. In traction treatment, the patient was in a sitting position, neck anteflexion at 15°–30°, traction force at 10%–20% of the body mass, for 20–30 min in each time. The treatment was given once every day. The appointed person evaluated therapeutic effects after the three sessions of treatment in the two groups. Results The clinical curative rate was 49.3% （37/75） and the total effective rate was 94.7% （71/75） in the acupuncture-moxibustion group and those were 24.0% （18/75） and 81.3% （61/75） respectively in the control group. The total effective rate and clinical curative rate in the acupuncture-moxibustion group were superior to the control group （both P0.05）. In the comparison of the duration of treatment and effect in the cured patients between the two groups, the curative rate in the 1st session of treatment in the acupuncture-moxibustion group was higher than that in the control group （P0.05）. In the comparison of the 6-month follow-up visit in the cured patients between the two groups, the effect in the acupuncture-moxibustion group was much more stable （P0.05）. Conclusion The warm needling therapy at EX-B 2 and tapping therapy with plum-blossom needle achieve the significant effect on cervical spondylosis of nerve root type.
基金by a project under the scheme entitled“Developing Policies&Adaptation Strategies to Climate Change in the Baltic Sea Region”(ASTRA),Project No.ASTRA6-4(2014-2020.4.01.16-0032).
文摘Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utilizing the reactive power capability of PV inverters to mitigate voltage deviations is being promoted.In recent years,droop control of inverter-based distributed energy resources has emerged as an essential tool for use in this study.The participation of PV systems in voltage regulation and its coordination with existing controllers,such as on-load tap changers,is paramount for controlling the voltage within specified limits.In this work,control strategies are presented that can be coordinated with the existing controls in a distributed manner.The effectiveness of the proposed method was demonstrated through simulation results on a distribution system.
基金supported by the National Natural Science Foundation of China(Grant Nos.61522109,61671253,61571037and 91738201)the Fundamental Research Funds for the Central Universities(No.2016JBZ006)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20150040and BK20171446)the Key Project of Natural Science Research of Higher Education Institutions of Jiangsu Province(No.15KJA510003)
文摘The fifth generation （5G） wireless communication is currently a hot research topic and wireless communication systems on high speed railways （HSR） are important applications of 5G technologies. Existing stud- ies about 5G wireless systems on high speed railways （HSR） often utilize ideal channel parameters and are usually based on simple scenarios. In this paper, we evaluate the down- link throughput of 5G HSR communication systems on three typical scenarios including urban, cutting and viaduct with three different channel estimators. The channel parameters of each scenario are generated with tapped delay line （TDL） models through ray-tracing sim- ulations, which can be considered as a good match to practical situations. The channel estimators including least square （LS）, linear minimum mean square error （LMMSE）, and our proposed historical information based ba- sis expansion model （HiBEM）. We analyze the performance of the HiBEM estimator in terms of mean square error （MSE） and evaluate the system throughputs with different channel estimates over each scenario. Simulation results are then provided to corroborate our proposed studies. It is shown that our HiBEM estimator outperforms other estimators and that the sys-tem throughput can reach the highest point in the viaduct scenario.
基金Project(NSC96-2221-E-233-005-MY2)supported by the National Science Council
文摘A machine vision for assessing and inspecting the ratio of thread areas associated with fixed frequency (FF) and limited tracing frequency (LTF) ultrasonic-assisted vibration was presented using differently coated taps after tapping of Ti-6Al-4V alloys.Experimental results indicate that TiAlN Micran taps yield the best tapping quality for different coatings and tapping conditions.TiAlN Micran coated taps with LTF make the largest improvement over traditional tapping (TT),with an average increase of 30.2%.
文摘Acacia senegal, the gum arabic producing tree, is the most important tree species for the livelihood of the people in South Kordofan State, Sudan. The objective of this study was to determine the optimum tapping date for gum arabic production in the study area. A randomized complete block design experiment with three replications was conducted at （Mead） area for two continuous growing seasons 2008/2009 - 2009/2010. The treatments comprised six tapping dates （1 Oct, 15 Oct, 1 Nov, 15 Nov, 1 Dec, and 15 Dec）. Results ishowed highly significant differences （p 〈 0.001） in gum arabic yield （g／tree） in all pickings and in the total gum yield between the tapping dates. The results also showed that tapping of trees on 15 October and 1 November gave a higher yield compared to the other dates. The highest gum yield of 1086.6 and 661.2 g/tree was recorded on 15 October and 15 November, while the lowest gum yield of 297.9 g/tree was recorded when the trees were tapped on 1 October. The two highest-yield dates of tapping （15 Oct and 1 Nov） are recommended as the best time for tapping for gum arabic production in South Kordofan State. These results can be used to increase gum arabic production and farmer income in South Kordofan State.
文摘The thermal conductivities of different typical species filling materials for sliding gate systems for steel ladles were measured using a hot wire technique, and the relationships between thermal conductivity and temperature were regressed. The factors affecting thermal conductivity were analyzed by using variance analysis for a perpendicular experiment. The effects of thermal conductivity on sliding gate free tapping were studied, and it was revealed that decreasing the thermal conductivity of the filling materials is beneficial in enhancing the rate of free tapping for sliding gates.
基金an independent research project from the Shandong Electric Power Research Institute,“Research on the control method of DC power under fixed converter transformer tap-changer position”(ZY-2020-01)Based on the achievement,a national invention patent(No.2020112240143)has been applied.
文摘Intermittent new energy delivery requires increasing the flexibility of ultra-high voltage direct current(DC)power adjustment.Based on a converter steady-state model and a DC power model,the control angle constraints of a converter valve are relaxed for power regulation.In this paper,a flexible DC power control method based on a fixed tap changer position is proposed.The initial ratio of the converter transformer is optimized.The effects of the fixed-tap changer position control on the control angle,reactive power compensation,and commutation failure are analyzed.The new control method allows a DC system to operate at a large angle and increase the additional reactive power loss while improving the commutation security margin.Steady-state and electromagnetic transient simulations in the CIGRE test system verify the validity of the method proposed in this paper and the correctness of the analysis conclusions.
基金Department of Science&Technology,Government of Rajasthan(India)
文摘Industrial applications of natural gums have been expanding tremendously, so gum collection from trees provides an important livelihood for local dwellers in drought-prone Rajasthan and its surroundings states. Traditional gum tapping is crude and unscientific; deep incision, untimely extraction and high concentration of chemicals in gum have affected Sterculia urens species in its natural habitat. In studies 2 years on trees having diameter at breast height 〉40 cm from natural stands to maximize gum collection and standardize the tapping method （bore holes vs. V blazes）, tapping season, chemical and concentration, different tapping techniques were tes- ted. For tapping maximum gum was collected using bore hole. Ethephon was better as extraction chemical than sulphuric acid. Bore-hole tapping with a 5-cm hole and ethephon at 300 mg/mL yielded the most gum （135.20 g/ tree）. Ethephon at 300 mg/mL yielded the most gum. Ethephon induced gummosis without affecting the health of tree. Tapping seasons also significantly affected the gum yield; the most gum was obtained in April-June.
基金Project supported by the National High-Tech Research and Development Program of China (Grant No. 2007AA12Z128)
文摘The periodic impact force induced by tip-sample contact in a tapping mode atomic force microscope （AFM） gives rise to the non-harmonic response of a micro-cantilever. These non-harmonic signals contain the full characteristics of tip-sample interaction. A complete theoretical model describing the dynamical behaviour of tip-sample system was developed in this paper. An analytic formula was introduced to describe the relationship between time-varying tip-sample impact force and tip motion. The theoretical analysis and numerical results both show that the timevarying tip-sample impact force can be reconstructed by recording tip motion. This allows for the reconstruction of the characteristics of the tip-sample force, like contact time and maximum contact force. It can also explain the ability of AFM higher harmonics imaging in mapping stiffness and surface energy variations.
基金Supported by the National Natural Science Foundation of China (60978007 61027007 61177067)
文摘A technique using artificial neural networks trained with parameters derived from delay tap plots for optical performance monitoring in 40 Gbit/s duobinary system is demonstrated. Firstly, the optical signal is delay tap sampled to obtain two-dimensional histogram, known as delay tap plots. Secondly, the features of delay tap plots are extracted to train the feed forward, three-layer preceptor structure artificial neural networks. Finally, the outputs of trained neural network are used to monitor optical duobinary signal impairments. Simulation of optical signal noise ratio （ OSNR）, chromatic dispersion （CD）, and differential group delay （DGD） monitoring in 40 Gbit/s optical duo- binary system is presented. The proposed monitoring scheme can accurately identify simultaneous impairments without requiring synchronous sampling or data clock recovery. The proposed technique is simple, cost-effective and suitable for in-service distributed OPM.
文摘The rubber tree Hevea brasiliensis(Willd.Ex Adr.De Juss.)Müell Arg.]is an important source of latex for the production natural rubber.Natural rubber is an important biopolymer used in various industries,but aspects related to hormonal regulation in biosynthesis are still unknown,which would allow optimizing its production.We review the molecular and physiological mechanisms of increases latex regeneration and flow by the stimulation of rubber trees with exogenous applications of ethylene and jasmonate.We found that the increase in latex regeneration by ethylene is due to the increase in gene level expression and enzymatic activity of key photosynthesis and glycolysis enzymes for the generation of precursors in the first phase of rubber biosynthesis.Latex flow is supported by up-regulated genes in sucrose metabolism such as invertases,induction of sucrose transporters(SUT),and aquaporins(PIP)to maintain flow and turgor pressure in laticifers.Meanwhile,the increase in latex yield mediated by jasmonate may be due to the induction of laticifer differentiation in the long term and in the short term be mediated by the induction of small rubber particles(SRPP)as non-enzymatic cofactors in the production of latex.This information contributes to the knowledge of latex biosynthesis,which allows for a greater support for the exogenous application of jasmonates and ethylene to regulate its production.
文摘A study was conducted in South Kordofan, Sudan to determine the effect of tapping, tapping tools and date of tapping on the gum yield of Acacia polyacantha. A two-factor experiment was conducted for two seasons in 2008-2009. One location was used for two seasons and two locations for one season. The first factor （4 levels） was the tools of tapping： Makmak, Farrar, and Sonki, and the control which was not tapped. The second factor （2 levels） was the date of tapping that comprises mid October and mid November. These treatments were arranged in Randomaized Complete Block Design and replicated three times. Gum yield （g/tree and g/ picking） was recorded for five pickings. Economic analysis was done using the partial budget technique. The results showed highly significant （p 〈 0.01） differences on gum yield （g/picking and g/tree）. The results indicated that the process of tapping increases gum production by 88.4% and 79.8% compared with un-tapped trees, respectively. The date of tapping has no significant effect on gum yield （g/tree and g/picking） of A. polyacantha. Tapping of the tree with Makmak in mid- November was found to be economically beneficial compared to using the other tools and the control. These results could identify a new source of income for the poor farmers in South Kordofan mainly because of the wild occurrence of Kakamut as a potential gum producing tree species grown naturally in the area.
文摘We conducted a two-factor experiment in randomized complete block design with four replications during 2004 in El Demokeya Forest Reserve and El Himaira Natural Forest, North Kordofan State, Sudan. The objective was to develop an understanding of the ecological effects of under-story vegetation and tapping date on the productivity of gum arabic from Acacia senegal as over story cover. The first factor was grass cover which was tested in four levels （100% and 50% grass cover in addition to bare and burnt）. The second factor, date of tapping was tested in three levels namely （1st Oct, 15th Oct and 1st Nov）. The first picking was done after 45 days from tapping and the gum yield up to seven pickings was collected at intervals of 15 days. Gum yield from each picking was collected and weighed using sensitive balance. Analysis of variance was carried out using MSTAT-C statistical package, and the Tukey test was applied for mean comparisons. The results showed highly significant differences （p 〈 0.01） of grass cover on gum arabic yield in the two sites for most of the first consecutive pickings （1st–4th out of seven） in addition to total yield （kg/ha）. With exception to the 4th pickings, the interaction effect between the grass densities and tapping date was not significantly different. The total gum yield was significantly （p 〈 0.05） increased in only two pickings （third and fourth） in El Demokeya Forest Reserve and two pickings （1st and 2nd） at El Himaira Natural Forest. The density of grass cover significantly （p 〈 0.05） affected the number of pickings at both sites; the number of gum pickings was directly proportional to grass density. The number of gum pickings was found to be significantly （p 〈 0.05） increased at the early date of tapping.
文摘An integrated Plate Mill has started it’s operation on July 7, 2010 in Gwangyang Steelworks, POSCO. The production capability is about 2.5 million tons per year and the main stream consists of Blast Furnace, Hot metal pretreatment (KR), Converter, Bubbling Station, RH/VTD and Continuous Casting. Particularly, it is possible to control sulfur concentration at excellent level in BOF without any further treatment in LF or VTD, which is attained by unique KR process and scrap usage strategy in BOF. In this paper, desulfurization efficiency and steel cleanliness was introduced by optimizing flux amount during tapping in BOF process. In addition, the effect of the flux addition on the refractory of ladle was investigated based on EPMA analyses with the viewpoint of phase diagram. The cleanliness of each sample was examined using optical emission spectrometry and oxygen nitrogen determinator.
基金The work was supported by the General Program of the National Natural Science Foundation of China(31,470,635)the Fundamental Research Funds of the Chinese Academy of Forestry(No.CAFYBB2017ZX001-3).
文摘Slash pine(Pinus elliottii Engelm.var.elliottii)is a resin-producing species grown worldwide for significant economic benefits for wood production.Resin tapping cre-ates a carbon sink at the expense of carbon allocation for growth and consequently,wood production may be reduced.Non-structural carbohydrates comprising starch and sugars stored in plant organs,may serve as intermediate pools between assimilation and utilisation.However,the effect of resin tapping between tree growth and non-structural carbo-hydrates is not well understood.This study investigated(1)the effects of resin tapping on radial growth,(2)the effects of resin tapping on non-structural carbohydrate pools in different compartments,and(3)the feasibility of resin pro-duction without disruption of tree growth.Twenty one-year-old slash pines were subjected to resin tapping over two suc-cessive years.Non-structural carbohydrate concentrations in needles,branches,stem phloem,and roots of tapped and untapped trees in summer and winter were determined after the second year of resin harvest.The results showed that tapping had no significant effects on annual increments.Starch was the dominant non-structural carbohydrate frac-tion,regardless of tissues and season,and constituted up to 99%of the total non-structural carbohydrates in the phloem and roots.Glucose and fructose were the dominant sugars;sucrose was negligible.Compared with the controls,tapped trees showed 26%lower non-structural carbohydrate concen-tration in the phloem above the tapping wound in summer,which was attributable to the decreased abundance of starch,glucose,fructose,and sucrose.In winter,the altered non-structural carbohydrate profiles in the phloem above the tap-ping wounding were minimised as a result of recovery of the sugar concentrations.In contrast to free sugars,which accu-mulated substantially in needles and branches during winter,starch was enriched in the phloem,roots,and current-year needles.The results provide evidence for a localised effect of resin tapping,and highlight the observation that resin extrac-tion does not always cause a sacrifice in wood growth under a moderate resin-tapping intensity in slash pine plantations.
