Search

Objective Sedimentary differences are the key factor in controlling reservoir heterogeneity. Analyzing reservoir heterogeneity through sedimentary microfacies is crucial for oil and gas field development and sweet spot prediction, and it also informs the evaluation of fracturing in tight sandstone reservoirs. There are many types and complex lithologies of unconventional oil and gas reservoirs in the Ordos Basin as well as many factors controlling reservoir fracability. At present, mechanical experiments are used to comprehensively characterize the fracturing property; however the research cost is high and the experimental process is complicated, making it unnsuitable for large-scale oilfield development and use. Therefore, this study attempted to analyze and compare the fracability of tight sandstones with different sedimentary microfacies from the perspective of sedimentary microfacies controlling the lithology and reservoir development to provide a reference for oilfield development plans. Methods Taking the compact sandstone of Chang 7 member of Yanchang Formation in the Longdong area of Ordos Basin as the research object, the different types of microfacies are identified through the data of core and cast slice, the mineral composition and structural parameters of rock samples were obtained by X-ray diffraction (XRD) analysis, and rock mechanics experiments were conducted to quantitatively described the fracturing property. Results The results are as follows: (1) Two sedimentary microfacies, namely underwater distributary channel and sheet sand, mainly developed in Chang 7 Member of Yanchang Formation in the study area. Among them, the single sand body thickness of the underwater distributary channel is greater than 2 m, the sheet sand is mostly a medium thin and thick sand mudstone interlayer, and the single sand body thickness is generally less than 2 m. (2) The composition and structure of the two sedimentary sandstone microfacies are obviously different: the content of carbonate minerals, clay minerals, and heterobases in the sheet sand microfacies are relatively high, the particle size is finer, and the sorting is worse, which are the main internal factors that cause the difference in tight sandstone fracability and are the basis for judging the fracability of tight sandstone by sedimentary microfacies. (3) The fracability index was related to the composition and structure of sandstone. In terms of composition, the fracability index was positively correlated with quartz mineral content as well as carbonate mineral content and negatively correlated with feldspar mineral content. In terms of structure, there is a negative correlation between the fracability index and the average particle diameter φ. The larger the particle size, the higher the fracability index. The fracability index was positively correlated with the standard deviation of the particle size, indicating that the worse the particle separation, the higher the fracability index. (4) Through grey correlation analysis, it was found that the degree of influence of sandstone parameters on fracability was in the order of carbonate mineral content, quartz content, standard deviation of particle size, and average particle size from high to low, while clay minerals and feldspar content were in a relatively weak position. Conclusion The results indicate that the higher the contents of carbonate and quartz and the higher the standard deviation of particle size (the worse the sorting), the better the fracability. The finer the particle size, the higher the feldspar content and the worse the fracability. Grey correlation analysis showed that the carbonate mineral content, separation and particle size play a major role in the fracability of tight sandstone. Compared with distributary channel microfacies, sheet sand has a higher carbonate minerals content, worse sorting, and little difference in quartz content. Although the microphase particle size of the sheet sand is slightly finer, the average particle size has a relatively minor effect on the fracability; thus, sheet sand as a whole shows better fracability. Significance Since the standard deviation (sorting) and particle size of sandstone particles are controlled by sedimentary microfacies, and the content of carbonate minerals is directly controlled by sandstone thickness and indirectly affected by sedimentary microfacies, the change in the tight sandstone fracability index can be judged according to the difference in sedimentary microfacies in practical engineering, and the working process can be simplified.

Flutter wind tunnel test is an important approach of investigation of transonic flutter characteristics of flight vehicle. Comparing with the blow-down wind tunnel, the long-running and low dynamic pressure capabilities of continuous transonic wind tunnel are very suitable for flutter test. The flutter safety protection and analysis of dynamic signals are developed. The safety protection control software, rapid reduction of Mach number and dynamic pressure, model debris catch screen are integrated, which can provide safety protection of test model and wind tunnel. During the test process, the flutter boundary can be achieved by interpolating the reciprocal of spectrum peak. The flutter tests of rudder are conduct through two methods of step and continuous varying dynamic pressure. It is illustrated that the error of flutter dynamic pressure is relatively small, less than 5% between the two methods. Meanwhile, the feedback effect of the real servo actuator on the flutter characteristics is hard to be obtained via numerical simulation. It is demonstrated that the flutter dynamic pressure has been increased by 10% due to the feedback effect.

Based on the physical parameters of the rocks (ores) and the genetic types of ore deposits, the geophysical exploration models have met issues of multiple solutions for deep prospecting prediction. It is necessary to find recognizable geological targets with high precision by geophysical methods. The ore prospecting practice over past years has demonstrated that the ore field tectonic deformation lithofacies belt is an outstanding target and significant prospecting results have been achieved. At present, the geophysical exploration work of large-scale mining area is heavy, while that of medium-scale ore field is limited, and both of them lack the strategic guidance at different levels. In order to establish the geophysical identification mark of the tectonic deformation lithofacies belt in ore field, it is necessary to clarify the complex time-space relationship between geology and geophysics, and strengthen the connection between geomechanics and geophysical exploration methods. In this paper, a method of processing and interpreting geophysical information at different levels is proposed. According to the "✳-shaped" structural features of the tectonic traces in the study area and the characteristics of the periodic development of the tectonic system, the geophysical exploration data of different scales and dimensions are analyzed from the two levels of ore field and deposit, and the information of tectonic deformation lithofacies belts is extracted. The specific operation procedures are as follows: (1) Making an area geophysical exploration within the scope of the ore field, interpreting the "✳-shaped" fault structure system, and then selecting the tensional and tension-torsional ore-bearing fault structures and predicting the prospecting direction; (2) Laying out large-deep geophysical profiles in the ore-bearing fault zone, analyzing the denudation degree and burial depth, and delineating the location of prospecting targets based on the geochemical exploration information. The application results of this method in the Chaihulanzi gold field in Chifeng, Inner Mongolia is introduced. The "✳-shaped" distribution of structural traces of the Neocathaysian tectonic system are interpreted from the geophysical data of the ore field, and then it is confirmed that the NNW and NWW trending tectonic deformation lithofacies belts are the main ore-bearing structural belts and there is a spatio-temporal sequential relationship between them in the two mining areas. These findings, provides a basis for deep ore prospecting and prediction.

Objective: To examine the association of body mass index (BMI) and waist circumference (WC) with frailty among oldest-old adults in China. Methods: A total of 7 987 people aged 80 years and older (oldest-old) who participated in the Chinese Longitudinal Healthy Longevity Survey (CLHLS) in 2017-2018 were included. Information on demographic characteristics, behavior pattern, diet, activities of daily living, cognitive function, health status, disease condition were collected by questionnaire and physical examination. Generalized linear mixed model and restricted cubic splines (RCS) were used to analyze the association of BMI and WC with frailty. Results: The mean age of all participants was 91.7 years, and their mean BMI and WC were (21.3±3.5) kg/m 2 and (82.9±10.5) cm, respectively. The proportion of male was 42.3% (3 377/7 987), and the proportion of people with frailty was 33.7% (2 664/7 987). After controlling confounding factors, compared with T 2 (19.1-22.1 kg/m 2 ) of BMI, the OR (95% CI ) of the female T 1 (<19.1 kg/m 2 ) and T 3 (≥22.2 kg/m 2 ) group was 1.39 (1.17-1.65) and 1.27 (1.07-1.52), respectively. Compared with T 2 (77-85 cm) of WC, the OR (95% CI ) of female T 1 (<77 cm) and T 3 (≥86 cm) group was 1.20 (1.01-1.42) and 1.10 (0.93-1.31), respectively. The results of multiple linear regression model with restrictive cubic spline showed that there was a non-linear association of BMI and WC with frailty in female. Conclusion: There is a U-shaped association of BMI and WC with frailty in female participants.

Objective: To explore the association between anemia and 3-year all-cause mortality among the oldest old people in longevity areas in China., Methods: In August 2012, questionnaire survey, health examination and blood test were conducted among 929 old people aged ≥ 80 years in 7 longevity areas in China, who were included in Chinese Longitudinal Healthy Longevity Survey (CLHLS) 2009. Cox regression model was used to evaluate the association between anemia or different hemoglobin levels and mortality., Results: Among the 929 subjects, the prevalence of anemia was 49.6%, the main form of anemia was normocytic anemia. During the three year follow-up period, a total of 447 subjects died, the overall mortality was 49.8% (56.0% in subjects with anemia and 43.3% in subjects without anemia). Compared with the subjects without anemia, the mortality risk increased by 25% in the subjects with anemia after adjusting confounding factors (HR = 1.25, 95% CI: 1.03-1.52). Macrocytic anemia, simplex microcytic anemia and microcytic hypochromic anemia were all associated with the increased mortality in the oldest old people. Compared with the subjects with low hemoglobin concentration, the subjects with high hemoglobin concentration had a lower mortality risk, and the association was more obvious in women., Conclusion: Anemia and low hemoglobin concentration were associated with higher mortality risk in the oldest old people in China, indicating the importance of anemia prevention and treatment among this population.

Objective: To understand the differences on sleeping-time between school-days and weekends among elementary school children., Methods: This cross-sectional study was conducted from September to November, 2010. A stratified random cluster sampling strategy was used to select the participants, under diverse geographical and economic levels in eight provinces, municipalities or autonomous regions, in mainland China. A total number of 20 603 elementary school children aged from 6-12 years old were chosen as research subjects to record their time of sleeping during school-days or weekends., Results: Among the 6-12 year old, their time of sleeping was longer on weekends than that on school-days, while the average sleeping time during the weekends was longer in boys than in girls (t = 3.35, P < 0.05). However, there was no linearly decreasing trend along with the increase of age regarding the time of sleeping on weekends, in girls. Proportions of serious lack of sleep, lack of sleep or with sufficient sleep during the weekends were 13.63% (2 809/20 603), 27.27% (5 618/20 603) and 59.10% (12 176/20 603). The proportion of sufficient sleep (over 50%) was significantly higher on weekends than that on school-days (less than 30%), however, nearly one third of the first grade primary school children were sleep insufficiently even on weekends. Nearly 10.00% of the children under seriously or moderately lack of sleep on school-days were still in a serious lack of sleep state on weekends. The three groups who were categorized as serious lack of sleep (less than 9 h), lack of sleep (9-10 h) or having sufficient (over 10 h) sleep on school-days accounted for 29.75%, 64.48%, 86.44%, respectively, when compared with the national regulation set as 10 h daily sleep for the children in China. The proportions of those whose time of sleep on weekends was less than school-days in the three groups as the same, moderate (within 1 h), with 1 h caught-up or over, were 9.41%, 22.77%, 43.32%, 24.50%, respectively. The percentage of pupils who caught up sleep appropriately (within 1 h) on weekends among those who were serious lack of sleep in school-days would exceed 40.00% while the proportions among those who lack of sleep or having sufficient on school-days were 54.00% and 30.00%. The percentage of children who slept less on weekends than on school-days among those having sufficient sleep on school-days appeared the highest, nearly 20.00%. However, the proportions among those who lack of sleep or seriously lack of sleep on school-days were 3.45% and 8.16%, respectively., Conclusion: We found that the elementary school children who could catch up time of sleep or lack of sleep on weekends coexisting in our study. This situation called for attention and the sleeping habit in primary school children should also be urgently improved.

Objective: To analyze the influencing factors for sleep duration of school children aged 6-12 years in school-day in 8 provinces in China., Methods: The cross sectional study was conducted among 20,603 children aged 6-12 years and selected through stratified random cluster sampling in 8 provinces (municipality and autonomous region) with different geographic characteristics and economic development level in China from September to November, 2010 to understand their sleep duration in school-day and related habits. t test and χ2 test were used to compare the sleep duration of the children. Multivariate stepwise logistic regression analysis was conducted to identify the influencing factors., Results: The survey indicated that the daily average sleep duration of the children in school days was 9.11 hours. The proportions of the children with serious insufficient sleep, insufficient sleep and sufficient sleep were 32.82% (7,672/20,603), 39.70% (8,179/20,603) and 27.48% (5,662/20,603), the children's sleep duration declined with age, so did proportion of children with serious insufficient sleep. There were no sex, urban or rural area and household income level specific significant differences in sleep duration among the children surveyed, and there were no sex specific differences in the proportion of children with serious insufficient sleep, insufficient sleep and sufficient sleep, however, these proportions were statistically different between urban area and rural area and among the regions with different economic level. The proportions of children with serious insufficient sleep and sufficient sleep was higher in rural area than in urban area (χ2=59.96, χ2=45.47, P<0.05), while the proportion of children with insufficient sleep was lower in rural area than in urban area. In the economy developed region, the proportion of children with insufficient sleep was lowest, the difference was statistical significant. After adjusting for sex, weight, diet and exercise time, multivariate logistic regression analysis showed that the factors benefiting children to have 10 hours sleep every day included having high protein diet, exercise, high household economic status and living in urban area., Conclusion: The problem of school children having insufficient sleep was serious in China, especially in the rural area.

Objective: To evaluate the status and trend of direct economic burden on cerebrovascular disease, from 1993 to 2008 in China., Methods: Using two-step model to calculate the economic cost with related trend of cerebrovascular disease within the population among the over 30-year-olds, from 1993 to 2008. Data was gathered from the National Health Service Surveys Analysis Reports of 1993, 1998, 2003 and 2008, that including both direct outpatient and inpatient cost., Results: There appeared a significant increase on the burden of cerebrovascular diseases in the period of 15 years, with direct economic cost increasing from 8.473 billion to 103.125 billion RMB. In fact, the actual increase was 5.3 times, without the influence of the price. The average annual growth rate was 13.1%, exceeding the rate of total expenditure on health and GDP during the same time span. In addition, the growth rate in 2003-2008 was the fastest, which appeared to be 19.8%., Conclusion: Burden that caused by cerebrovascular disease on individuals and the whole society was heavy which warrented further theoratical and practical studies on it.

Objective: To assess the policies and programs on the capacity of prevention and control regarding non-communicable diseases (NCDs) at the Centers for Disease Control and Prevention (CDCs) at all levels and grass roots health care institutions, in China., Methods: On-line questionnaire survey was adopted by 3 352 CDCs at provincial, city and county levels and 1 200 grass roots health care institutions., Results: 1) On policies: 75.0% of the provincial governments provided special funding for chronic disease prevention and control, whereas 19.7% city government and 11.3% county government did so. 2) Infrastructure:only 7.1% county level CDCs reported having a department taking care of NCD prevention and control. 8 263 staff members worked on NCDs prevention and control, accounting for 4.2% of all the CDCs' personnel. 40.2% CDCs had special funding used for NCDs prevention and control. 3)Capacity on training and guidance:among all the CDCs, 96.9% at provincial level, 50.3% at city level and 42.1% at county level had organized training on NCDs prevention and control. Only 48.3% of the CDCs at county level provided technical guidance for grass-roots health care institutions. 4) Capacities regarding cooperation and participation: 20.2% of the CDCs had experience in collaborating with mass media. 5) Surveillance capacity: 64.6% of the CDCs at county level implemented death registration, compare to less than 30.0% of CDCs at county level implemented surveillance programs on major NCDs and related risk factors. In the grass roots health care institutions, 18.6% implemented new stroke case reporting system but only 3.0% implemented program on myocardial infarction case reporting. 6) Intervention and management capacity: 36.1% and 32.2% of the CDCs conducted individualized intervention on hypertension and diabetes, while less than another 20% intervened into other NCDs and risk factors. More than 50% of the grass roots health care institutions carried follow-up survey on hypertension and diabetes. Rates on hypertension and diabetes patient management were 12.0% and 7.9% , with rates on standard management as 73.8% and 80.1% and on control as 48.7% and 50.0%, respectively. 7) Capacity on Assessment: 13.3% of the CDCs or health administrations carried out evaluation programs related to the responses on NCDs in their respective jurisdiction. 8) On scientific research: the capacity on scientific research among provincial CDCs was apparently higher than that at the city or county level CDCs., Conclusion: Policies for NCDs prevention and control need to be improved. We noticed that there had been a huge gap between county level and provincial/city level CDCs on capacities related to NCDs prevention and control. At the grass-roots health care institutions, both prevention and control programs on chronic diseases did not seem to be effective.

Objective: To understand the situation and efficacy of community-based management programs on hypertension and type 2 diabetes mellitus patients in primary health service centers., Methods: In eight provinces being selected, a stratified multistage random sampling method was used to survey 5 116 cases of hypertension patients and 3 586 cases of type 2 diabetes mellitus patients aged over 35 years who had been under the management program for over 1 year. Face-to-face questionnaire interview and physical and biochemical examination were applied to collect related information, blood pressure and situation of glucose control., Results: The rates of management on hypertension patients and type 2 diabetes mellitus patients were 23.6% (urban:17.1%, rural:28.1%, χ² = 27 195.33, P < 0.001)and 19.1% (urban:14.1%, rural:23.8%, χ² = 7 423.67, P < 0.001)while the standardized management rates were 61.1% (urban:63.3%, rural:58.6%, χ² = 11.82, P < 0.001)and 59.0% (urban:61.5%, rural:55.6%, χ² = 12.66, P < 0.001), respectively. Rate on blood pressure control among hypertension patients and the rate on fasting glucose control on type 2 diabetes mellitus patients were 50.3% (urban:62.0%, rural:36.6%, χ² = 329.31, P < 0.001)and 53.9% (urban:60.8%, rural:44.7%, χ² = 90.53, P < 0.001), respectively. Satisfaction rates for the management service of the hypertension patients and type 2 diabetes mellitus patients were 83.0% (urban:84.7% , rural: 80.7% , χ² = 13.42, P < 0.001) and 84.5% (urban:88.0% , rural:79.5% , χ² = 43.90, P < 0.001), respectively., Conclusion: Efficiency was achieved to some extent in managing hypertension and type 2 diabetes mellitus patients in primary health service centers. Further improvement was expected on rates regarding management, standardized management and control on both blood pressure and glucose.

Objective: To analyze the relationship between birth weight and elevated blood pressure among schoolchildren aged 6-11 years in 8 provinces of China., Method: A stratified random cluster sampling was used from sampling frame of eight provinces in the mainland of China. A total of 18 920 students aged 6-11 years eventually participated in this study. Height, weight, waist circumference (WC) and blood pressure of all the subjects were measured. Korotkoff I and V were recorded as systolic blood pressure (SBP) and diastolic blood pressure (DBP). Elevated blood pressure was considered for SBP and/or DBP equal to or above the reference sex-, age- and height-specific 95th percentile. Birth weight and family history of hypertension were collected by self-administered questionnaire. Analysis of variance was used to compare body measure indicators among 3 birth weight groups. Multivariate Logistic regression analysis was performed to identify the relationship between birth weight, current BMI and elevated blood pressure among children., Result: The level of height, weight, WC, BMI, SBP and DBP were on the rise with the increase of the birth weight groups among boys (P < 0.05), except for WC among boys aged 6-8 years. The level of height, weight, WC, BMI and DBP showed a trend of escalation among girls (P < 0.05). But, SBP among 3 birth weight groups in girls was not significantly different (P = 0.099). After adjusting for age and family history of hypertension, compared with the normal birth weight group, the odds ratio and 95%CI of having elevated blood pressure among boys and girls in high birth weight group were 1.23 (1.06-1.43) and 0.89 (0.71-1.10), respectively; and the ORs(95%CI) were 1.06 (0.90-1.24) for boys and 0.73 (0.58-0.91) for girls after adjusting for age, family history of hypertension and current BMI of students. The relative risk of elevated blood pressure for boys and girls in low birth weight group were not significantly different as compared with normal birth weight group., Conclusion: Current BMI but not birth weight was found to be a strong determinant of elevated blood pressure among children aged 6-11 years in China.