Space Interval Research Articles

On the limits of stabilizability for networks of strings

An example by Bastin and Coron illustrates that the boundary stabilization of 1-d hyperbolic systems with certain source terms is only possible if the length of the space interval is sufficiently small.We show that related phenomena also occur for networks of vibrating strings that are governed by the wave equation with a certain source term. It turns out that for a tree of strings with Neumann velocity feedback control at one boundary node and a homogeneous Dirichlet boundary condition at at least one boundary node and homogeneous Dirichlet or Neumann conditions at the other boundary nodes, boundary feedback stabilization is not possible if one of the strings is sufficiently long. However, if the number of strings in the tree is sufficiently large, also for arbitrarily short strings for certain parameters in the source term stabilization is not possible.The wave equation with source term that we consider is equivalent to a certain 2 ×2 system. For the examples that illustrate the limits of stabilizability, the matrix of the source term is not positive definite. However if the system parameters are chosen in such a way that the matrix is positive semi-definite, the tree of strings can be stabilized exponentially fast by the boundary feedback control for arbitrary long space intervals.

METHODS EVALUATING UPPER ARM AND FOREARM MOVEMENT DURING A QUIET STANCE

The article focuses on designing methods for quantitative assessment of the postural stability in a quiet stance by measuring segments of the appendicular skeleton, namely upper and forearms by inertial measurement units (IMU). Although an array of quantitative analysis methods assessing data of postural stability in the quiet stance exist by measuring the head and trunk movement, these methods have not been used to date to assess the behaviour of appendicular skeleton segments, namely the upper limbs. The applicability of methods assessing arm movement during the quiet stance has been verified by comparing the values of healthy subjects performing various stance tasks. The tests determined the quantitative evaluation of acceleration measured on individual anatomical axes. The quantities included: the volume of a convex polyhedron (PV), the volume of confidence ellipsoid (EV) and average velocity (AV) obtained by plotting three accelerations against each other. The most important findings in this study concern significant differences of PV and AV between dominant and non-dominant upper extremities and significant differences of EV, PV and AV between the data measured with a subject's eyes closed and open. Higher values of indicators were in the non-dominant extremities when subjects were measured with closed eyes. Interestingly, statistically significant differences between dominant and non-dominant arm movements were documented in PV and AV cases. This is due to the PV calculation being more sensitive to random deviations, i.e. the range of measured data, since the polyhedron bounds all the measured data, as opposed to the method, where the ellipse bounds only 95% of the measured data. In the case of the AV method, it is due to higher sensitivity to movements corresponding with arm tremors; the AV calculation relates not only to the range of measured data but, above all, to the intensity of data changes in the segment measured in a particular space and time interval. These conclusions demonstrate that it is possible to apply the proposed methods in the assessment of arm movement during a quiet stance since the differences between individual stance tasks and the dominant and non-dominant arms in specific cases of quiet stance have been identified. These conclusions also indicate a potentially more extensive medical application of the proposed quantitative data evaluation obtained from IMU, for example, within the rehabilitation process of injured appendicular skeleton segments. The use of cheaper IMU methods in mobile phones or watches can be of significant benefit in measuring the segmental movement of the appendicular skeleton in quiet stance. The methods outlined in this paper have remarkable potential in the field of telemedicine.

Ionospheric Peak Parameters Retrieved from FY-3C Radio Occultation: A Statistical Comparison with Measurements from COSMIC RO and Digisondes Over the Globe

In this study, two ionospheric peak parameters (ICPs), NmF2 and hmF2, derived from the global navigation satellite system (GNSS) radio occultation (RO) ionospheric electron density profiles (EDPs) obtained by Feng-Yun 3C (FY-3C) mission are compared with those derived from the observations of the Constellation Observing System for the Meteorology, Ionosphere, and Climate (COSMIC) mission and the measurements from 24 digisonde stations distributed around the world during the year from 2014 to 2017. The FY-3C derived ICPs and the COSMIC-derived ICPs are provided by the National Satellite Meteorological Centre (NSMC) and the COSMIC Data Analysis and Archive Center (CDAAC), respectively. The correlation and bias analyses are carried out in the comparison under the collocation criterion with the time interval of 1 h and the space interval of 3° in latitude and 5° in longitude. When comparing the ICPs derived from the two RO missions, the difference in the azimuth of occultation planes (DAOPs) between the matched pairs is limited to be within 20°. The comparison results are analyzed for different solar activity periods, and solar elevation angle (SEA) is taken for the first time as a factor that represents the comprehensive impacts of latitude zones, seasons, and local time of the observations. The results are shown as follows: (1) Both the COSMIC RO-derived and the digisonde-observed ICPs are in good agreement with the FY-3C RO-derived ones. The correlation coefficient (CC) between the NmF2 and hmF2 derived by COSMIC RO and FY-3C RO is 0.965 and 0.916, respectively, while the correlation coefficient between the NmF2 and hmF2 derived by digisonde and FY-3C RO is 0.924 and 0.832, respectively. The quality of FY-3C RO-derived ICPs are reliable enough for further applications. (2) The CC of NmF2 is, in general, higher than that of hmF2 when comparing FY-3C RO with other observations, and the overall MAB and MRB of FY-3C RO-derived ICPs during the higher solar activity period are higher than the ones during the lower solar activity period. The difference between the two RO missions is much smaller than that one between FY-3C RO and digisonde. (3) For a certain solar activity period, the standard deviations of the absolute bias (SDAB) and the standard deviations of the relative bias (SDRB) of FY-3C RO-derived ICPs compared with digisonde-derived ones generally increases with the increase of SEA, while the SDAB and SDRB of FY-3C RO-derived ICPs both get the minimum values for the AOP interval near to 90°.

A new analytical model for flow in acidized fractured-vuggy porous media

Acidizing is one of the widely used technologies that makes the development of naturally fractured-vuggy reservoirs effective. During the process of acidizing, carbonate minerals are dissolved by hydrochloric acid, which can create high conductivity channels and wormholes to connect fractures and pores. In this work, a new analytical model, incorporating the heterogeneity of the pore networks into acidizing region, is proposed to study the flow characteristics in acidized fractured-vuggy reservoirs. The model is coupled by an acidized inner region and a conceptualized outer region of common triple medium. The porosity and permeability of inner region, which are rather heterogeneous and disordered when observed at different length scales, can be well addressed by fractal theory. The properties of the outer region can be described with three basic parameters: the matrix block size LM, the space interval of fracture LF and the radius of the vug Lv. Results show that the flow characteristic curves can be characterized by six flow stages (i.e. wellbore storage stage, radial flow stage in the interior region, fracture-vug inter-porosity flow stage, transition flow stage, fracture-matrix inter-porosity flow stage and external boundary response stage). It can be applied to estimate reservoir parameters for uncertainty reduction using inverse modeling.

Maternal Risk Factors Associated with Low Birth Weight in Ibn al-Baladi Hospital in Baghdad Governorate

Background: low birth weight is a reliable indicator in monitoring and evaluating the success of maternal and child health programs and has been defined as a birthweight less than 2500 grams. Aims of study: to determine the mean birthweight of the studied sample and to identify factors associated with the low birth weight. Methodology: A cross-sectional study conducted in Baghdad in Ibn Al-Baladi hospital. Sampling was convenient & sample size was 200. The study started from 1st October 2016 to 30th March 2017. Data was collected by questionnaire to obtain social- demographic information. Results: The result shows that mean weight of cases was 2.09 kg as compared to 3.5kg in controls, and the 12% were illiterate. About (36.9%) of the women with low birthweight were mainly at less than 37 weeks of gestation age , the number of women who had more than one child was higher among LBW than among normal birthweight. Analysis of results by (chi-square test) show that low educational level, preterm, short birth space interval less than 2 years, and multigravida, and low ANC visits and smoking were significant factors associated with low birthweight Conclusions: This study shows the low educational level, medical and obstetric and low visit antenatal clinic and smoking factors have strong association with low birth weight. Recommendation: The study re commended that re gular health education program through mass media and regular education program in ANC units for pregnant women to avoiding LBW babies.

Quantum Field Theory Description of Processes Passing at Finite Space and Time Intervals

We consider a new approach to the quantum field theory description of processes passing at finite space-time intervals. The formalism is based on the Feynman diagram technique in the coordinate representation supplemented with modified rules for the transition to the momentum representation reflecting specific experimental situations. This effectively implies that only the particle propagators in the momentum representation are modified, while the standard Feynman rules in the momentum representation remain unchanged. No wave packets are used in the approach, i.e., the initial and final states of particles are described by plane waves, which significantly simplifies the calculations. Three processes—neutrino oscillations, unstable particle decay, and neutral kaon oscillations—are used as examples to show that the proposed approach correctly reproduces the well-known results.

On non-autonomously forced Burgers equation with periodic and Dirichlet boundary conditions

AbstractWe study the non-autonomously forced Burgers equation $$u_t(x,t) + u(x,t)u_x(x,t)-u_{xx}(x,t) = f(x,t)$$ on the space interval (0, 1) with two sets of the boundary conditions: the Dirichlet and periodic ones. For both situations we prove that there exists the unique H1 bounded trajectory of this equation defined for all t ∈ ℝ. Moreover we demonstrate that this trajectory attracts all trajectories both in pullback and forward sense. We also prove that for the Dirichlet case this attraction is exponential.

On the Dynamics of Zero-Speed Solutions for Camassa–Holm-Type Equations

Abstract In this paper, we consider globally defined solutions of Camassa–Holm (CH)-type equations outside the well-known nonzero-speed, peakon region. These equations include the standard CH and Degasperis–Procesi (DP) equations, as well as nonintegrable generalizations such as the $b$-family, elastic rod, and Benjamin-Bona-Mahony (BBM) equations. Having globally defined solutions for these models, we introduce the notion of zero-speed and breather solutions, i.e., solutions that do not decay to zero as $t\to +\infty $ on compact intervals of space. We prove that, under suitable decay assumptions, such solutions do not exist because the identically zero solution is the global attractor of the dynamics, at least in a spatial interval of size $|x|\lesssim t^{1/2-}$ as $t\to +\infty $. As a consequence, we also show scattering and decay in CH-type equations with long-range nonlinearities. Our proof relies in the introduction of suitable virial functionals à la Martel–Merle in the spirit of the works of [74, 75] and [50] adapted to CH-, DP-, and BBM-type dynamics, one of them placed in $L^1_x$ and the 2nd one in the energy space $H^1_x$. Both functionals combined lead to local-in-space decay to zero in $|x|\lesssim t^{1/2-}$ as $t\to +\infty $. Our methods do not rely on the integrable character of the equation, applying to other nonintegrable families of CH-type equations as well.

Time domain subdivision method for optical grating signal based on time series analysis

Aiming at the restriction of the Moire signal quality on the subdivision multiple and accuracy, a time domain subdivision method for optical grating signals based on time series analysis is proposed. The relationship between the grating pitch and the sampling period is utilized to transform the equal space intervals into time series. A time domain prediction model is established based on the autoregressive model of time series analysis to predict the sampling time, and the parameters of the model are calculated using the maximum likelihood estimate method. Experimental results indicate that the subdivision errors both achieve ± 2.4 when the subdivision multiples are 400 and 800, respectively. This subdivision method reduces the reliance on grating signal quality, proving certain application value.

Description of processes passing at finite space and time intervals in the framework of QFT

We consider a new approach to the description in the framework of QFT of processes passing at finite space and time intervals. The formalism is based on the Feynman diagram technique in the coordinate representation, in which the rules of passing to the momentum representation are modified in accordance with the experimental setup of neutrino oscillation experiments. In effect, only the propagators of particles in the momentum representation are modified, while all the other standard Feynman rules in the momentum representation remain the same. Since the initial and final particle states are described by plane waves, the approach does not need the use of wave packets, which greatly simplifies the calculations of amplitudes. Taking as examples the processes of displaced pion decay, neutral kaon and neutrino oscillations we show that the approach under consideration correctly reproduces the known standard results.

R2* relaxometry in sclerotic hippocampi of patients with temporal lobe epilepsy

Chapter 7 focuses on the computation of one-dimensional channel flow by the numerical method of characteristics. Techniques for construction of the characteristic network are presented. The methods of specified space and time intervals are developed, and are used to solve the dam-break problem. The chapter also addresses the computation of one-dimensional channel flow by finite-difference methods. Conservative and non-conservative formulations are explored. The two-step Lax-Wendroff and Preissmann methods are analyzed. Shock capturing and non-reflecting boundary conditions are described in detail. Fourier analysis of systems of first-order hyperbolic equations is carried out, and the conditions for stability of explicit schemes are examined. Finally, this chapter extends the finite element and finite-volume methods to open-channel flow. The emphasis is on monotonicity preserving methods and shock capturing. The Riemann problem is introduced, and flux limiting is used to construct TVD schemes for open-channel flow.

基于光纤测温技术的城市地表温度精细化分析

PDF HTML阅读 XML下载 导出引用 引用提醒 基于光纤测温技术的城市地表温度精细化分析 DOI: 10.5846/stxb201802060310 作者: 作者单位: 中国科学院生态环境研究中心 城市与区域生态国家重点实验室,中国科学院生态环境研究中心 城市与区域生态国家重点实验室,中国科学院生态环境研究中心 城市与区域生态国家重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划资助（2016YFC0503605） Refined analysis of urban surface temperature based on optical fiber temperature measurement technology Author: Affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences,State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences Fund Project: National Key Research And Development Plan(2016YFC0503605) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:城市景观空间构型与热岛效应关联性较强，研究高时空分辨率的城市不同下垫面地表温度变化，可以更加精细地掌握城市热环境的时空特征。光纤温度传感系统具有实时在线、测温精度高和不受电磁干扰等优点，具备实时、在线、连续开展城市地表温度在线监测的能力。在北京市通州某园区内，选择有太阳辐射的4个时段，对多种类型下垫面的地表温度进行了时间间隔为1 min、空间间隔为1 m的连续4 h、总长度为100 m的实时在线监测。通过对监测时间段内不同类型下垫面地表温度的变化分析，发现这种分布式光纤测温系统能够有效辨识小尺度下地表温度的时间变化性和空间变化性，能有效区分透水和不透水地面，并监测和评估沥青马路地表温度的升温速率以及遮荫效果对地表温度的降温作用。同时，这种监测模式获取的数据能够对地表温度空间序列开展自相关分析，进一步验证了地表温度空间序列在较小尺度上仍然具有自相关性，且距离越近，相关性越大。研究同时表明，光纤测温技术能直接地获取城市热环境的现场真实数据，可以有效应用于小尺度城市热环境的观测与研究。 Abstract:The spatial configuration of the urban landscape is highly correlated with the heat island effect. By studying the land surface temperature (LST) of different underlying surfaces with high spatial and temporal resolution, we can grasp the temporal and spatial characteristics of the urban thermal environment more accurately. The optical fiber temperature sensing system has the advantages of real-time and high measurement accuracy and immunity to electromagnetic interference, and can monitor the LST in real time and continuously. In a park in Tongzhou, Beijing, four periods with solar radiation were selected, and the LST of various types of underlying surfaces was recorded in four consecutive hours with 1-minute time interval and 1-meter space interval, and the total length was 100 m. By analyzing the changes of LST of different underlying surface, it's proved that this distributed optical fiber temperature measurement system can effectively identify temporal and spatial variability of LST on a small scale, distinguish between permeable and impervious grounds, monitor the heating rate of the surface temperature of asphalt road, and evaluate the cooling effect of shading on LST. At the same time, data obtained by this monitoring mode enables autocorrelation analysis of LST spatial sequence. The results verified that the LST spatial sequence still has autocorrelation on a small scale, and the closer the distance, the higher the correlation level. Simultaneously, it is confirmed by this practice that the optical fiber temperature measurement technology can be effectively applied to the observation and research of small-scale urban thermal environment. 参考文献 相似文献 引证文献

Two-point Output Feedback Boundary Control for Semilinear Hyperbolic Systems

A new control problem is posed and solved: regulation problem for the one-dimensional Klein-Gordon and semilinear wave equations with Neumann boundary conditions in the case when the control acts at both ends of the space interval (“two-point control”). A control algorithm based on the speed-gradient method is proposed. The global exponential stability of the closed loop system for the case of the Klein-Gordon equation is established by means of a new Lyapunov functional. This results is extended to the case of the semilinear wave equation by means of linearization. The two-point energy control problem for the sine-Gordon and semilinear wave equations is analyzed by simulation. It is demonstrated that the proposed two-point control algorithm may provide 30% faster transients.

A stochastic model for intracellular active transport

We develop a stochastic model for an intracellular active transport problem. Our aims are to calculate the probability that a molecular motor reaches a hidden target, to study what influences this probability and to calculate the time required for the molecular motor to hit the target (Mean First Passage Time). We study different biologically relevant scenarios, which include the possibility of multiple hidden targets (which breed competition) and the presence of obstacles. The purpose of including obstacles is to illustrate actual disruptions of the intracellular transport (which can result, for example, in several neurological disorders. From a mathematical point of view, the intracellular active transport is modelled by two independent continuous-time, discrete space Markov chains: one for the dynamics of the molecular motor in the space intervals and one for the domain of target. The process is time homogeneous and independent of the position of the molecular motor.

Existence, Asymptotics, Stability and Region of Attraction of a Periodic Boundary Layer Solution in Case of a Double Root of the Degenerate Equation

For a singularly perturbed parabolic problem with Dirichlet conditions we prove the existence of a solution periodic in time and with boundary layers at both ends of the space interval in the case that the degenerate equation has a double root. We construct the corresponding asymptotic expansion in the small parameter. It turns out that the algorithm of the construction of the boundary layer functions and the behavior of the solution in the boundary layers essentially differ from that ones in case of a simple root. We also investigate the stability of this solution and the corresponding region of attraction.

Factors Affecting Birth Space Interval of Women Who Are Attending Primary Health Care Centers

Objective: The aim of this study is to determine the factors affecting birth space interval in a sample of women.Methodology: A cross-sectional study conducted in primary health centers in Al-Tahade and Al- Shak Omar inBaghdad city. Data were collected by direct interview using questionnaire especially prepared for the study.Sample size was (415) women in age group (20-40) years who were chosen randomly.Results: Analysis of data shows highest rate of women (31.8%) had a birth space interval of (8-12) monthsfollowed by (26.7%) had a birth space interval of (19-24) months, (20.2%) had a birth space interval of (>24)months and (16.1%) had a birth space interval of (13-18) months respectively, while lower rate of women (5.1%)had birth space interval of (7) months. The birth space interval was higher in age group (20) years. Also, thisinterval was prolonged by the use of contraceptives, breast feeding and women who had a high level ofeducation.Analysis of data shows that (age group, level of education, occupation, use of contraceptives, parity and numberof abortion) were significant factors associated with birth space interval by using P-value of less than 0.01 wasconsidered significant to test the result.Recommendations: Concentrated effort should be made to emphasize the risk of close birth spacing for both ofthe mother and infant, in all our primary health centers as well as the family planning centers should be includedin these efforts explaining the importance of breast feeding for adequate birth spacing.

A stochastic model for active transport

We develop a stochastic model for an intracellular active transport problem. Our aims are to calculate the probability that a molecular motor reaches a hidden target, to study what influences this probability and to calculate the time required for the molecular motor to hit the target (mean first passage time). We study different biologically relevant scenarios, which include the possibility of multiple hidden targets (which breed competition) and the presence of obstacles. The purpose of including obstacles is to illustrate actual disruptions of the intracellular transport (which can result, for example, in several neurological disorders. From a mathematical point of view, the intracellular active transport is modelled by two independent continuous-time, discrete space Markov chains: one for the dynamics of the molecular motor in the space intervals and one for the domain of target. The process is time homogeneous and independent of the position of the molecular motor.

Sensory and motor parameter estimation for elbow myoelectric control with vibrotactile feedback

Despite technological advances upper limb prosthesis, myoelectric control requires a long learning process. The absence of sensory feedback is very likely to impinge the appropriation of the prosthesis. We explored a sensory substitution alternative with various configurations and settings for vibrotactile feedback and myoelectric parameters. Six vibrators were placed on a line or circumferentially around the arm. Space intervals between vibrators were absolute (2 cm) or proportional to the length or the circumference of the arm. Dispositions as longitudinal proportional and absolute, circular proportional and absolute were tested. Sixty, 100 and 140 ms of duration and intensities of 62.5; 100; and 167 mA were explored. Estimate location of the vibration, and perceived intensity between 0 (no feeling) to 3 (strong) were assessed. EMGs from biceps and triceps were recorded during isometric contraction to control the elbow velocity of an avatar displayed on a screen. EMGs were filtered and normalized from maximal contraction. A threshold of minimum muscle activity and a gain of the velocity control were adjusted to allow fast an intuitive control. The circular proportional disposition elicited better discrimination results than the 3 others dispositions ( P < 0.05). Duration, intensity and disposition were all found to influence the success rate scores (3 ways ANOVA P < 0.0001). Stimulations with small duration (60 ms) were perceived as being produced with a lower level of intensity. A threshold between 5 and 7.5% of the maximum force, and a velocity gain varying from 0.3 to 1.2 rad.s-1 for a change in muscle contraction of 10% MVC were found to enable precise control of the avatar. The circular proportional disposition of the vibrator is a well suited configuration for sensory substitution. Our next step will be to combine sensory feedback given by vibrator to the myoelectric control. This sensory substitution could improve prosthesis control, and may attenuate phantom limb pain.

A Study of Endometrial Perfusion in Unexplained Infertility

Background: Infertility in itself represents a wide spectrum of disorders explaining the inability to conceive. Series of investigations are required to depict the potential cause of infertility, yet there exist a small percentage (10 -25%) of couples in which no obvious cause is delineated. these groups of patients are classified as ‘unexplained infertility. The endometrium has dynamic features: cyclical growth, desquamation and regeneration. Its main function is to provide the possibility of the time-limited support of implantation of the embryo for further development. Most part of the menstrual cycle, the endometrium is resistant to the embryo but acquires special receptive properties in a limited space and time interval of the luteal phase, known as the ‘‘implantation window’’. Aim: The aim of this study was to evaluate the uterine perfusion, particularly the endometrial blood flow in women with unexplained infertility. Methodology: The patients recruited from women presenting to the outpatient clinic at Ain Shams University Maternity Hospital seeking fertility compared to other fertile group coming to hospital with non specific gynecological problems or for routine checkup at the same period. The study conducted on two groups of women: Group1(study group) 40 women with unexplained infertility, Group 2 (control group) 20 fertile women who had normal physical and pelvic examination, regular menstrual cycles, didn't have intrauterine device or oral contraceptive, and gave a birth year ago. Results: As regard the mean, the resistance index in the study group was 0.69 ranged from 0.39 to 0.96, while the resistance index in the control group was 0.61 ranged from 0.58 to 0. 73 and the difference between both groups was statistically significant pulsatility index in the study group was 1.3 ranged from 0.51 to 1.99 while the pulsatility index in the control group was 1.16 ranged from 0.88 to 1.7 and this difference between both groups was statistically significant. From the results of our study we could say that uterine perfusion, particularly the endometrial blood flow in women with unexplained infertility different from that in fertile women. Recommendation: We recommend further study on large numbers of women and the possible role of perfusion enhancer's drugs in improving utero-ovarian circulation as a treatment of unexplained infertility.

A Study of Endometrial Perfusion in Unexplained Infertility

Background: Infertility in itself represents a wide spectrum of disorders explaining the inability to conceive. Series of investigations are required to depict the potential cause of infertility, yet there exist a small percentage (10 -25%) of couples in which no obvious cause is delineated. these groups of patients are classified as ‘unexplained infertility. The endometrium has dynamic features: cyclical growth, desquamation and regeneration. Its main function is to provide the possibility of the time-limited support of implantation of the embryo for further development. Most part of the menstrual cycle, the endometrium is resistant to the embryo but acquires special receptive properties in a limited space and time interval of the luteal phase, known as the ‘‘implantation window’’. Aim: The aim of this study was to evaluate the uterine perfusion, particularly the endometrial blood flow in women with unexplained infertility. Methodology: The patients recruited from women presenting to the outpatient clinic at Ain Shams University Maternity Hospital seeking fertility compared to other fertile group coming to hospital with non specific gynecological problems or for routine checkup at the same period. The study conducted on two groups of women: Group1(study group) 40 women with unexplained infertility, Group 2 (control group) 20 fertile women who had normal physical and pelvic examination, regular menstrual cycles, didn't have intrauterine device or oral contraceptive, and gave a birth year ago. Results: As regard the mean, the resistance index in the study group was 0.69 ranged from 0.39 to 0.96, while the resistance index in the control group was 0.61 ranged from 0.58 to 0. 73 and the difference between both groups was statistically significant pulsatility index in the study group was 1.3 ranged from 0.51 to 1.99 while the pulsatility index in the control group was 1.16 ranged from 0.88 to 1.7 and this difference between both groups was statistically significant. From the results of our study we could say that uterine perfusion, particularly the endometrial blood flow in women with unexplained infertility different from that in fertile women. Recommendation: We recommend further study on large numbers of women and the possible role of perfusion enhancer's drugs in improving utero-ovarian circulation as a treatment of unexplained infertility.