Bicycling constitutes an integral component of sustainable non-motorized means of travel. Despite the immense benefits of bicycling, the modal share of bicycling is quite low, specifically among young and low-income c...Bicycling constitutes an integral component of sustainable non-motorized means of travel. Despite the immense benefits of bicycling, the modal share of bicycling is quite low, specifically among young and low-income commuters e.g., college and university students. This study explores the perceptions of and barriers to bicycling of the campus community at the University of Tennessee, Knoxville with the aim to identify the factors that could enhance bike use among students at the university campus as well as highlight the barriers that keep young population away from biking. An online survey about bike use at the university campus was administered and responses to the survey were recorded. On the methodological front, a binary logit model was estimated with students’ willingness to use bikes at campus as the dependent variable. The survey results revealed that about 47% of the students considered vehicular traffic as the reason for feeling unsafe while biking and emphasized having separate bike routes. Most of the respondents highlighted the need to change clothes after biking in summer or carry things as the reason for not selecting bikes as a mode of transport at the campus, whereas inadequate bike lanes, paths, or trails, insufficient lighting along bike routes, and the lack of adequate bicycle parking were highlighted as the major barriers deterring bike use within the campus. The study suggests development of a campus bike network with proper bike lanes, bike runnels, installation of safety cameras and better lighting at the campus, and bike-supporting infrastructure such as communal showers to be provided in campus buildings to encourage bike use among university students. The study findings can assist campus transportation planners in devising a sustainable campus transportation plan incorporating the influencing factors and deterrents of bike use in a university campus setting.展开更多
The title compounds 3-（3,5-bis（trifluoromethyl）phenyl）quinoline （1） and 3-（4- fluoro-3-methylphenyl）quinoline （2） were synthesized through Suzuki-Miyaura Cross coupling reaction of 3-bromoquinoloine with ary...The title compounds 3-（3,5-bis（trifluoromethyl）phenyl）quinoline （1） and 3-（4- fluoro-3-methylphenyl）quinoline （2） were synthesized through Suzuki-Miyaura Cross coupling reaction of 3-bromoquinoloine with aryl boronic acids. The title compounds were characterized by single-crystal X-ray diffraction, 1H NMR, 13C NMR, El-MS, elemental analysis and IR. The crystals of 3-（3,5-bis（trifluoromethyl）phenyl）quinoline （C17H9F6N, Mr = 341.25） belongs to the monoclinic system, space group P21n, a = 12.3072（13）, b = 4.9378（6）, c = 24.493（2） A, V= 1473.1（3） A3, Z = 4, Dc = 1.539 Mg m-3, 2 - 0.71073A, μ = 0.144 mm^-1, F（000） = 688, the final R = 0.0715 and wR = 0.1873 for 1875 obserwed reflections with I 〉 2σ（I） and the crystal of 3-（4-fluoro-3- methylphenyl）quinoline （C16H12FN, Mr= 237.27） belongs to the orthorhombic system, space group Pca21, a = 23.794（2）, b = 3.9094（3）, c = 25.669（2） A, V = 2387.7（4） A3, Z = 8, D, = 1.320 Mg m-3, 2 = 0.71073 A, μ = 0.088 mm-1, F（000） = 992, the final R = 0.0534 and wR = 0.1188 for 2270 observed reflections with I 〉 2σ（I）.展开更多
The title compound （E）-ethyl 2-fluoro-2-（3-oxoisobenzofuran-1（3H）-ylidene） aceta- te was synthesized as an unexpected product by the reaction ofphthalyl dichloride with bis-silylenol ether, which is not in accor...The title compound （E）-ethyl 2-fluoro-2-（3-oxoisobenzofuran-1（3H）-ylidene） aceta- te was synthesized as an unexpected product by the reaction ofphthalyl dichloride with bis-silylenol ether, which is not in accordance with our previous studies. The title compound was characterized by single-crystal X-ray diffraction, 1H NMR, 13C NMR, 19F NMR, GCMS, HRMS and IR. The crystal （C12HgFO4, Mr = 236.19） belongs to the monoclinic system, space group P21/c, a = 19.1609（8）, b = 7.9831（3）, c = 13.7715（6） A, V= 2106.13（15） A3, Z= 8, Dx = 1.490 Mg m-3, MoKa radiation, 2 = 0.71073 A,μ = 0.12 mm-1, F（000） = 976, the final R = 0.025 and wR = 0.1300 for 4505 observed reflections with I〉 2σ（I）.展开更多
The peer-to-peer（P2P） file-sharing network as a vehicle of disseminating files has become very popular. The appearance of dozens of kinds of passive worms on this network has, however, made it unsecured. This proble...The peer-to-peer（P2P） file-sharing network as a vehicle of disseminating files has become very popular. The appearance of dozens of kinds of passive worms on this network has, however, made it unsecured. This problem has been paid attention and a few of models for passive worm propagation has been presented. Unfortunately, the dynamic properties of this network are ignored in these models. Given the fact, the characteristics of both this network and the passive worm are identified, and on this basis a new mathematical model of passive worm propagation on the P2P network is presented in applying epidemiology in this paper. Note that the dynamic properties of this network are considered in the presented model. The model has been validated by large scale simulation experiments, which demonstrates that the presented model may be used for analyzing the behaviors of passive worms and predicting the trend of their propagation.展开更多
In this paper, an effective dynamic equation of a three link manipulator for a control purpose has been dealt with by the Euler-Lagrange method. The structural properties of the derived dynamic equation were proved so...In this paper, an effective dynamic equation of a three link manipulator for a control purpose has been dealt with by the Euler-Lagrange method. The structural properties of the derived dynamic equation were proved so that the vast control strategies developed for the serial counterparts can be easily extended for controlling the three link manipulator. In addition, it is illustrated how to design a PD controller for the robot manipulator by making use of computed torque method strategy to develop our controller. Simulation results are included in order to depict the performance of the controller.展开更多
Lithium's(Li)ubiquitous distribution in the environment is a rising concern due to its rapid proliferation in the modern electronic industry.Li enigmatic entry into the terrestrial food chain raises many questions...Lithium's(Li)ubiquitous distribution in the environment is a rising concern due to its rapid proliferation in the modern electronic industry.Li enigmatic entry into the terrestrial food chain raises many questions and uncertainties that may pose a grave threat to living biota.We examined the leverage existing published articles regarding advances in global Li resources,interplay with plants,and possible involvement with living organisms,especially humans and animals.Globally,Li concentration(<10 e300 mg kg1)is detected in agricultural soil,and their pollutant levels vary with space and time.High mobility of Li results in higher accumulation in plants,but the clear mechanisms and specific functions remain unknown.Our assessment reveals the causal relationship between Li level and biota health.For example,lower Li intake(<0.6 mM in serum)leads to mental disorders,while higher intake(>1.5 mM in serum)induces thyroid,stomach,kidney,and reproductive system dysfunctions in humans and animals.However,there is a serious knowledge gap regarding Li regulatory standards in environmental compartments,and mechanistic approaches to unveil its consequences are needed.Furthermore,aggressive efforts are required to define optimum levels of Li for the normal functioning of animals,plants,and humans.This review is designed to revitalize the current status of Li research and identify the key knowledge gaps to fight back against the mountainous challenges of Li during the recent digital revolution.Additionally,we propose pathways to overcome Li problems and develop a strategy for effective,safe,and acceptable applications.展开更多
In this contribution, we reported a novel approach to crosslink poly(ε-caprolactone)(PCL) via supramolecular hydrogen bonding interactions. First, a series of octa-armed poly(ε-caprolactone) stars with polyhedral ol...In this contribution, we reported a novel approach to crosslink poly(ε-caprolactone)(PCL) via supramolecular hydrogen bonding interactions. First, a series of octa-armed poly(ε-caprolactone) stars with polyhedral oligomeric silsesquioxane(POSS) cores were synthesized via the ring-opening polymerizations. Thereafter, the arm ends of organic-inorganic star-shaped PCLs were reacted with 2-(6-isocyanatohexylaminocarbonylamino)-6-methyl-4[1 H]-pyrimidinone to obtain 2-ureido-4[1 H]-pyrimidone(UPy)-terminated PCL stars.Notably, the UPy-terminated PCL stars were physically crosslinked, which was evidenced by means of dynamic mechanical thermal analysis(DMTA) and rheological analysis. Owing to the formation of the physically-crosslinked networks, the organic-inorganic PCL stars displayed significant shape memory properties with about 100% of shape recovery, which was in marked contrast to the PCL stars without UPy termini.展开更多
Precision planters are important machines in the regime of modern technological agriculture.Field conditions,seed metering system and machine operating parameters affect the pneumatic planter performance.The pneumatic...Precision planters are important machines in the regime of modern technological agriculture.Field conditions,seed metering system and machine operating parameters affect the pneumatic planter performance.The pneumatic planter was evaluated to determine the effect of three tillage levels(L1,L2,and L3)and four travel speeds(S1,S2,S3 and S4).The sowing uniformity of the planter was observed with respect to the horizontal distribution of seeds within a row and described by using the precision index(Ip),the multiple index(Imult),the miss-seeding index(Imiss)and the quality of feed index(Iqf).The results revealed that the tillage levels(L)and travel speed(S)had a significant effect(p<0.05)on dependent variables.The maximum Imiss(22.12%)was observed at L1 and S4 whereas the maximum Imult was observed at L1 and S1.The mean values of missing-,multi-,quality-feed and precision indices were 5.14%,5.833%,89.03%and 17.85%at L3,respectively.The mean values of multi-index 17.59%,14.44%,12.40%and 10.18%,quality feed index 74.07%,75.92%,75.74%and 74.07%and precision indices 21.47%,23.26%,25.51%and 28.53%were at S1,S2,S3 and S4,respectively.The study showed that maize could be seeding within an acceptable precise range by bed-type pneumatic planter subjected to the proper seedbed preparation level.展开更多
In this Letter, we have proposed a generalized Gaussian probability density function（GGPDF）-based method to estimate the symbol error ratio（SER） for pulse amplitude modulation（PAM-4） in an intensity modulation/d...In this Letter, we have proposed a generalized Gaussian probability density function（GGPDF）-based method to estimate the symbol error ratio（SER） for pulse amplitude modulation（PAM-4） in an intensity modulation/direct detection（IM/DD） system. Furthermore, a closed form expression of SERGGDfor PAM-4 has been derived. The performance of the proposed method is evaluated through simulation as well as experimental work.The fitting of probability density functions of the received signal is applied via GGPDF and shape parameters P1 and P2 associated with different PAM-4 levels are determined. The optimum single value of shape parameter P is then calculated to estimate the SER. The mathematical relationship of P with different received optical powers and receiver bandwidths has been determined and verified. The proposed method is a fast and accurate method to estimate SER of a PAM-4 system, which is more reliable and in agreement with the error counting method.展开更多
文摘Bicycling constitutes an integral component of sustainable non-motorized means of travel. Despite the immense benefits of bicycling, the modal share of bicycling is quite low, specifically among young and low-income commuters e.g., college and university students. This study explores the perceptions of and barriers to bicycling of the campus community at the University of Tennessee, Knoxville with the aim to identify the factors that could enhance bike use among students at the university campus as well as highlight the barriers that keep young population away from biking. An online survey about bike use at the university campus was administered and responses to the survey were recorded. On the methodological front, a binary logit model was estimated with students’ willingness to use bikes at campus as the dependent variable. The survey results revealed that about 47% of the students considered vehicular traffic as the reason for feeling unsafe while biking and emphasized having separate bike routes. Most of the respondents highlighted the need to change clothes after biking in summer or carry things as the reason for not selecting bikes as a mode of transport at the campus, whereas inadequate bike lanes, paths, or trails, insufficient lighting along bike routes, and the lack of adequate bicycle parking were highlighted as the major barriers deterring bike use within the campus. The study suggests development of a campus bike network with proper bike lanes, bike runnels, installation of safety cameras and better lighting at the campus, and bike-supporting infrastructure such as communal showers to be provided in campus buildings to encourage bike use among university students. The study findings can assist campus transportation planners in devising a sustainable campus transportation plan incorporating the influencing factors and deterrents of bike use in a university campus setting.
文摘The title compounds 3-（3,5-bis（trifluoromethyl）phenyl）quinoline （1） and 3-（4- fluoro-3-methylphenyl）quinoline （2） were synthesized through Suzuki-Miyaura Cross coupling reaction of 3-bromoquinoloine with aryl boronic acids. The title compounds were characterized by single-crystal X-ray diffraction, 1H NMR, 13C NMR, El-MS, elemental analysis and IR. The crystals of 3-（3,5-bis（trifluoromethyl）phenyl）quinoline （C17H9F6N, Mr = 341.25） belongs to the monoclinic system, space group P21n, a = 12.3072（13）, b = 4.9378（6）, c = 24.493（2） A, V= 1473.1（3） A3, Z = 4, Dc = 1.539 Mg m-3, 2 - 0.71073A, μ = 0.144 mm^-1, F（000） = 688, the final R = 0.0715 and wR = 0.1873 for 1875 obserwed reflections with I 〉 2σ（I） and the crystal of 3-（4-fluoro-3- methylphenyl）quinoline （C16H12FN, Mr= 237.27） belongs to the orthorhombic system, space group Pca21, a = 23.794（2）, b = 3.9094（3）, c = 25.669（2） A, V = 2387.7（4） A3, Z = 8, D, = 1.320 Mg m-3, 2 = 0.71073 A, μ = 0.088 mm-1, F（000） = 992, the final R = 0.0534 and wR = 0.1188 for 2270 observed reflections with I 〉 2σ（I）.
文摘The title compound （E）-ethyl 2-fluoro-2-（3-oxoisobenzofuran-1（3H）-ylidene） aceta- te was synthesized as an unexpected product by the reaction ofphthalyl dichloride with bis-silylenol ether, which is not in accordance with our previous studies. The title compound was characterized by single-crystal X-ray diffraction, 1H NMR, 13C NMR, 19F NMR, GCMS, HRMS and IR. The crystal （C12HgFO4, Mr = 236.19） belongs to the monoclinic system, space group P21/c, a = 19.1609（8）, b = 7.9831（3）, c = 13.7715（6） A, V= 2106.13（15） A3, Z= 8, Dx = 1.490 Mg m-3, MoKa radiation, 2 = 0.71073 A,μ = 0.12 mm-1, F（000） = 976, the final R = 0.025 and wR = 0.1300 for 4505 observed reflections with I〉 2σ（I）.
文摘The peer-to-peer（P2P） file-sharing network as a vehicle of disseminating files has become very popular. The appearance of dozens of kinds of passive worms on this network has, however, made it unsecured. This problem has been paid attention and a few of models for passive worm propagation has been presented. Unfortunately, the dynamic properties of this network are ignored in these models. Given the fact, the characteristics of both this network and the passive worm are identified, and on this basis a new mathematical model of passive worm propagation on the P2P network is presented in applying epidemiology in this paper. Note that the dynamic properties of this network are considered in the presented model. The model has been validated by large scale simulation experiments, which demonstrates that the presented model may be used for analyzing the behaviors of passive worms and predicting the trend of their propagation.
文摘In this paper, an effective dynamic equation of a three link manipulator for a control purpose has been dealt with by the Euler-Lagrange method. The structural properties of the derived dynamic equation were proved so that the vast control strategies developed for the serial counterparts can be easily extended for controlling the three link manipulator. In addition, it is illustrated how to design a PD controller for the robot manipulator by making use of computed torque method strategy to develop our controller. Simulation results are included in order to depict the performance of the controller.
基金funded by the The 111 project of the Education Ministry of China(B18053)The National Natural Science Foundation(32130081).
文摘Lithium's(Li)ubiquitous distribution in the environment is a rising concern due to its rapid proliferation in the modern electronic industry.Li enigmatic entry into the terrestrial food chain raises many questions and uncertainties that may pose a grave threat to living biota.We examined the leverage existing published articles regarding advances in global Li resources,interplay with plants,and possible involvement with living organisms,especially humans and animals.Globally,Li concentration(<10 e300 mg kg1)is detected in agricultural soil,and their pollutant levels vary with space and time.High mobility of Li results in higher accumulation in plants,but the clear mechanisms and specific functions remain unknown.Our assessment reveals the causal relationship between Li level and biota health.For example,lower Li intake(<0.6 mM in serum)leads to mental disorders,while higher intake(>1.5 mM in serum)induces thyroid,stomach,kidney,and reproductive system dysfunctions in humans and animals.However,there is a serious knowledge gap regarding Li regulatory standards in environmental compartments,and mechanistic approaches to unveil its consequences are needed.Furthermore,aggressive efforts are required to define optimum levels of Li for the normal functioning of animals,plants,and humans.This review is designed to revitalize the current status of Li research and identify the key knowledge gaps to fight back against the mountainous challenges of Li during the recent digital revolution.Additionally,we propose pathways to overcome Li problems and develop a strategy for effective,safe,and acceptable applications.
基金financially supported by the National Natural Science Foundation of China(Nos.51133003,21274091,and21774078)
文摘In this contribution, we reported a novel approach to crosslink poly(ε-caprolactone)(PCL) via supramolecular hydrogen bonding interactions. First, a series of octa-armed poly(ε-caprolactone) stars with polyhedral oligomeric silsesquioxane(POSS) cores were synthesized via the ring-opening polymerizations. Thereafter, the arm ends of organic-inorganic star-shaped PCLs were reacted with 2-(6-isocyanatohexylaminocarbonylamino)-6-methyl-4[1 H]-pyrimidinone to obtain 2-ureido-4[1 H]-pyrimidone(UPy)-terminated PCL stars.Notably, the UPy-terminated PCL stars were physically crosslinked, which was evidenced by means of dynamic mechanical thermal analysis(DMTA) and rheological analysis. Owing to the formation of the physically-crosslinked networks, the organic-inorganic PCL stars displayed significant shape memory properties with about 100% of shape recovery, which was in marked contrast to the PCL stars without UPy termini.
基金The authors acknowledge that this work was supported by the Key Research and Development Project(Grant No.2016YFD0200708)Key Research and Development Project(Modern Agriculture)of Jiangsu Province(Grant No.BE2020328,BE2017354)and the Funded Project by Bahauddin Zakariya University,Multan(DR&EL/D-740 dated 11-10-2017),Pakistan.
文摘Precision planters are important machines in the regime of modern technological agriculture.Field conditions,seed metering system and machine operating parameters affect the pneumatic planter performance.The pneumatic planter was evaluated to determine the effect of three tillage levels(L1,L2,and L3)and four travel speeds(S1,S2,S3 and S4).The sowing uniformity of the planter was observed with respect to the horizontal distribution of seeds within a row and described by using the precision index(Ip),the multiple index(Imult),the miss-seeding index(Imiss)and the quality of feed index(Iqf).The results revealed that the tillage levels(L)and travel speed(S)had a significant effect(p<0.05)on dependent variables.The maximum Imiss(22.12%)was observed at L1 and S4 whereas the maximum Imult was observed at L1 and S1.The mean values of missing-,multi-,quality-feed and precision indices were 5.14%,5.833%,89.03%and 17.85%at L3,respectively.The mean values of multi-index 17.59%,14.44%,12.40%and 10.18%,quality feed index 74.07%,75.92%,75.74%and 74.07%and precision indices 21.47%,23.26%,25.51%and 28.53%were at S1,S2,S3 and S4,respectively.The study showed that maize could be seeding within an acceptable precise range by bed-type pneumatic planter subjected to the proper seedbed preparation level.
文摘In this Letter, we have proposed a generalized Gaussian probability density function（GGPDF）-based method to estimate the symbol error ratio（SER） for pulse amplitude modulation（PAM-4） in an intensity modulation/direct detection（IM/DD） system. Furthermore, a closed form expression of SERGGDfor PAM-4 has been derived. The performance of the proposed method is evaluated through simulation as well as experimental work.The fitting of probability density functions of the received signal is applied via GGPDF and shape parameters P1 and P2 associated with different PAM-4 levels are determined. The optimum single value of shape parameter P is then calculated to estimate the SER. The mathematical relationship of P with different received optical powers and receiver bandwidths has been determined and verified. The proposed method is a fast and accurate method to estimate SER of a PAM-4 system, which is more reliable and in agreement with the error counting method.
