考虑轴向大拉伸下弹性模量对聚酯系泊动态响应的影响

Owing to the particularity of a polyester fiber material,the polyester mooring undergoes large axial tensile deformation over long-term use.Large axial tensile deformation significantly impacts the dynamic response of the mooring system.In addition,the degrees of large axial tension caused by different elastic moduli are also different,and the force on the mooring line is also different.Therefore,it is of great significance to study the influence of elastic modulus on the dynamic results of the mooring systems under large axial tension.Conventional numerical software fails to consider the axial tension deformation of the mooring.Based on the theory of slender rods,this paper derives the formula for large axial tension using the method of overall coordinates and overall slope coordinates and provides the calculation programs.Considering a polyester mooring system as an example,the calculation program and numerical software are used to calculate and compare the static and dynamic analyses to verify the reliability of the calculation program.To make the force change of the mooring obvious,the elastic moduli of three different orders of magnitude are compared and analyzed,and the dynamic response results after large axial tension are compared.This study concludes that the change in the elastic modulus of the polyester mooring changes the result of the vertex tension by generating an axial tension.The smaller the elastic modulus,the larger the forced oscillation motion amplitude of the top point of the mooring line,the more obvious the axial tension phenomenon,and the smaller the force on the top of the polyester mooring.

An improved binarization algorithm of wood image defect segmentation based on non-uniform background

In this study,an image binarization optimization algorithm,based on local threshold algorithms,is proposed because global and traditional local threshold segmentation algorithms cannot effectively address the problems of nonuniform backgrounds of wood defect images.The proposed algorithm calculates the threshold by the mean,standard deviation and the extreme value of the window.The results indicate that this modified algorithm enhances the image segmentation for wood defect images on a complex background,which is much superior to the global threshold algorithm and the Bernsen algorithm,and slightly better than the Niblack algorithm and Sauvola algorithm.Compared with similar models,the algorithm proposed in this paper has higher segmentation accuracy,as high as 92.6%for wood defect images with a complex background.

Experimental Investigation of the Characteristics of an Artificial Cavity During the Water-Exit of a Slender Body

Experimental studies are carried out with slender bodies vertically exiting out of the water using a high-speed camera. The mechanisms for the formation, development, and collapse of the cavity around the slender body are explored. The dynamic characteristics of the shoulder cavity and the trail cavity during the water-exit of low-speed bodies are analyzed for various water depths and initial velocities. The results show that the initial velocity has a great influence on the formation, development, and collapse of the cavity. The length and the thickness of the shoulder cavity vary non-linearly with the depth.

PGC-MG7 combination could be used as a follow-up panel for monitoring dynamical progression of gastric precancerous diseases

Objective: The aim of this study was to investigate the value of the combined expression of the gastric mucosal differentiation protein pepsinogen C(PGC) and gastric cancer(GC)-associated antigen MG7 for the diagnosis of GC and prediction of the development from precancerous conditions to GC.Methods: The gastric mucosal biopsies of 285 subjects enrolled from a region with a high incidence of GC were obtained and histopathologically examined. Subjects testing negative for GC(n=208) were followed up from 1998 to 2015. The levels of PGC and MG7 in the biopsies were determined by immunohistochemistry.Results: PGC was positive in 91.4% of the non-atrophic gastritis, 26.5% of the atrophic gastritis, and 0% of the GC. MG7 was positive in 15.0% of the non-atrophic gastritis, 82.4% of the atrophic gastritis, and 94.8% of the GC. The non-atrophic gastritis group was predominantly "PGC+MG7-". The atrophic gastritis and GC groups were predominantly "PGC-MG7+". The rate of GC in subjects with "PGC-MG7+" staining was 113.4-fold higher [95% confidence interval(95% CI): 15.3-869.4, P<0.001] than that in subjects with other staining patterns.The sensitivity and specificity of the "PGC-MG7+" pattern were 92.2% and 78.8% for the detection of GC and77.2% and 97.9% for GC and precancerous disease, respectively. In the follow-up cohort of non-GC subjects, the risk of developing GC was higher in those with the "PGC-MG7+" staining pattern.Conclusions: Our data suggest that the "PGC-MG7+" pattern can be employed as a useful follow-up panel for detecting individuals with a high risk of GC, and the dynamic assessment of the follow-up panel needs multi-centre large-scale validation in the future.

Research on the Viscoelasticity of Polyester Mooring Lines Using the Absolute Nodal Coordinate Formulation

The taut mooring system using synthetic fiber ropes has overcome the shortcomings such as the large self-weight of the mooring lines and provides better mooring performance for the floating structures.The polyester rope has attracted much attention among numerous synthetic fiber rope materials due to its lightweight,low price,corrosion resistance,and high strength.Thus,the mooring characteristics of it are worth studying.Polyester mooring lines are flexible in deep water,when a marine structure is moored by them,the geometric nonlinearity such as large displacement,large stretch,and large bending deformation,and the material nonlinearity like viscoelastic of the polyester ropes become complex integrated problems to be studied.Considering the nonlinear phenomenon,the simulation and calculation of a polyester line were carried out by the absolute nodal coordinate formulation(ANCF)in this paper since the ANCF method has advantages in dealing with the significant deformation problems of the flexible structures.In addition,a chain mooring line was also simulated for comparison,and the results show that the polyester ropes reduce the self-weight of the mooring lines and provide sufficient mooring strength at the same time,and the nonlinear phenomenon of the polyester ropes is different from that of the chain mooring lines.

Surveillance of pine wilt disease by high resolution satellite

Pine wilt disease caused by the pinewood nematode Bursaphelenchus xylophilus has led to the death of a large number of pine trees in China.This destructive disease has the characteristics of bring wide-spread,fast onset,and long incubation time.Most importantly,in China,the fatality rate in pines is as high as 100%.The key to reducing this mortality is how to quickly find the infected trees.We proposed a method of automatically identifying infected trees by a convolution neural network and bounding box tool.This method rapidly locates the infected area by classifying and recognizing remote sensing images obtained by high resolution earth observation Satellite.The recognition accuracy of the test data set was 99.4%,and the remote sensing image combined with convolution neural network algorithm can identify and determine the distribution of the infected trees.It can provide strong technical support for the prevention and control of pine wilt disease.

Forest fire smoke recognition based on convolutional neural network

Traditional fire smoke detection methods mostly rely on manual algorithm extraction and sensor detection;however,these methods are slow and expensive to achieve discrimination.We proposed an improved convolutional neural network(CNN)to achieve fast analysis.The improved CNN can be used to liberate manpower.The network does not require complicated manual feature extraction to identify forest fire smoke.First,to alleviate the computational pressure and speed up the discrimination efficiency,kernel principal component analysis was performed on the experimental data set.To improve the robustness of the CNN and to avoid overfitting,optimization strategies were applied in multi-convolution kernels and batch normalization to improve loss functions.The experimental analysis shows that the CNN proposed in this study can learn the feature information automatically for smoke images in the early stages of fire automatically with a high recognition rate.As a result,the improved CNN enriches the theory of smoke discrimination in the early stages of a forest fire.

Risk Management of Key Issues of FPSO

Risk analysis of key systems have become a growing topic late of because of the development of offshore structures. Equipment failures of offioading system and fire accidents were analyzed based on the floating production, storage and offioading （FPSO） features. Fault tree analysis （FTA）, and failure modes and effects analysis （FMEA） methods were examined based on information already researched on modules of relex reliability studio （RRS）. Equipment failures were also analyzed qualitatively by establishing a fault tree and Boolean structure function based on the shortage of failure cases, statistical data, and risk control measures examined. Failure modes of fire accident were classified according to the different areas of fire occurrences during the FMEA process, using risk priority number （RPN） methods to evaluate their severity rank. The qualitative analysis of FTA gave the basic insight of forming the failure modes of FPSO offioading, and the fire FMEA gave the priorities and suggested processes. The research has practical importance for the security analysis problems of FPSO.

Reduction of electric field strength by two species of trees under power transmission lines

Electrical pollution is a worldwide concern,because it is potentially harmful to human health.Trees not only play a significant role in moderating the climate,but also can be used as shields against electrical pollution.Shielding effects on the electric field strength under transmission lines by two tree species,Populus alba and Larix gmelinii,were examined in this study.The electrical resistivity at different heights of trees was measured using a PiCUS sonic tomograph,which can image the electrical impedance for trees.The electric field strength around the trees was measured with an elf field strength measurement system,HI-3604,and combined with tree resistivity to develop a model for calculating the electric field intensity around trees using the finite element method.In addition,the feasibility of the finite element method was confirmed by comparing the calculated results and experimental data.The results showed that the trees did reduce the electric field strength.The electric field intensity was reduced by 95.6%,and P.alba was better than L.gmelinii at shielding.

Experimental Research of Hull Vibration of a Full-Scale River Icebreaker

A series of tests of a full-scale river icebreaker was conducted to investigate the characteristics of ice-induced hull vibration.The test was conducted when the river icebreaker was operating in an ice-covered river at temperatures of-4 to 0°C with ice thicknesses of 300 to 400 mm.In the tests,the ice condition and icebreaker speed were chosen as the main influence factors.By analyzing the measured test data,we identified some important points regarding ice-induced hull vibration.When the river icebreaker navigates in an area with complete ice coverage,the peak value of the acceleration amplitude spectrum is highest.Also,the vibration response excited by the icebreaking load in an area with complete ice coverage exhibits more frequencies.With an increase in icebreaker speed,the vibration acceleration response gradually increases.However,habitability of the bow region on the main and driving decks is maintained due to the harmless vibration levels.In addition,the icebreaking operation of the river icebreaker causes violent local vibration of the grillage on the main deck.

Fluorouracil-based preoperative chemoradiotherapy with or without oxaliplatin for stage Ⅱ/Ⅲ rectal cancer:a 3-year follow-up study

Background： Fluorouracil-based preoperative chemoradiotherapy has become the standard treatment for stage Ⅱ/Ⅲ rectal cancer. In order to improve the overall survival （OS） and disease-flee survival （DFS）, we added oxaliplatin to the standard treatment, and compared the effectiveness of these two treatment patterns. Methods： A total of 206 patients enrolled in the prospective study had histologically confirmed rectal cancer of clinical stage Ⅱ/Ⅲ during July 2007 to July 2010. They were randomized into the experimental group received oxaliplatin and capecitabine in combination with radiotherapy, and the control group received capecitabine in combination with radiotherapy. All patients received surgery in 6-10 weeks after chemoradiotherapy and adjuvant chemotherapy with mFOLFOX6. The primary endpoints were DFS and OS, and the secondary endpoints included toxicity, compliance, and histopathological response. Results： The 3-year OS in the experimental group and the control group was 90.29% vs. 86.41% （P〉0.05）, and the 3-year DFS was 80.58% vs. 69.90% （P〉0.05）. The pathological complete remission （pCR） rates were 23.30% and 19.42%, respectively （P=0.497）. The 3-year local recurrence rates were 4.85% vs. 5.83% （P=0.694）, and the 3-year distant metastasis rates were 16.50% and 28.16%, respectively （P=0.045）. There were no significant differences in most grade 3-4 toxicities between two groups, however, grade 3-4 diarrhea occurred in 16.50% （17/103） of the experimental group, compared with 6.80% （7/103） of the control group （P=0.030）. Also, the total grade 3-4 acute toxicity showed a significant difference （10.68% vs. 21.36%, P=0.037）. Conclusions： The experimental treatment did not lead significantly improved OS and DFS, and thus longer follow-up is warranted for our patient cohort. Adding oxaliplatin to capecitabine-based preoperative chemoradiotherapy can significantly reduce metastasis, but has only minimal impact on local recurrence. Although grade 3-4 toxicity rate increased （primarily gastrointestinal toxicity）, patients can stand to be followed up with allopathic treatment.

Development of Optimal Maintenance Policies for Offshore Wind Turbine Gearboxes Based on the Non-homogeneous Continuous-Time Markov Process

Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of offshore wind farms. From their initial perfect working states, gearboxes degrade with time, which leads to decreased working efficiency. Thus, offshore wind turbine gearboxes can be considered to be multi-state systems with the various levels of productivity for different working states. To efficiently compute the time-dependent distribution of this multi-state system and analyze its reliability, application of the nonhomogeneous continuous-time Markov process(NHCTMP) is appropriate for this type of object. To determine the relationship between operation time and maintenance cost, many factors must be taken into account, including maintenance processes and vessel requirements. Finally, an optimal repair policy can be formulated based on this relationship.

Strength Reliability Analysis of Stiffened Cylindrical Shells Considering Failure Correlation

The stiffened cylindrical shell is commonly used for the pressure hull of submersibles and the legs of offshore platforms. There are various failure modes because of uncertainty with the structural size and material properties, uncertainty of the calculation model and machining errors. Correlations among failure modes must be considered with the structural reliability of stiffened cylindrical shells. However, the traditional method cannot consider the correlations effectively. The aim of this study is to present a method of reliability analysis for stiffened cylindrical shells which considers the correlations among failure modes. Firstly, the joint failure probability calculation formula of two related failure modes is derived through use of the 2D joint probability density function. Secondly, the full probability formula of the tandem structural system is given with consideration to the correlations among failure modes. At last, the accuracy of the system reliability calculation is verified through use of the Monte Carlo simulation. Result of the analysis shows the failure probability of stiffened cylindrical shells can be gained through adding the failure probability of each mode.

Comparison of Segmentation Algorithms for Detecting Myocardial Infarction Using Late Gadolinium Enhancement Magnetic Resonance Imaging

Objective:The aim of this study was to validate the accuracy of a new automatic method for scar segmentation and compare its performance with that of two other frequently used segmentation algorithms.Methods:Twenty-six late gadolinium enhancement cardiovascular magnetic resonance images of diseased hearts were segmented by the full width at half maximum(FWHM)method,the n standard deviations(n SD)method,and our new automatic method.The results of the three methods were compared with the consensus ground truth obtained by manual segmentation of the ventricular boundaries.Results:Our automatic method yielded the highest Dice score and the lowest volume difference compared with the consensus ground truth segmentation.The n SD method produced large variations in the Dice score and the volume difference.The FWHM method yielded the lowest Dice score and the greatest volume difference compared with the automatic,6SD,and 8SD methods,but resulted in less variation when different observers segmented the images.Conclusion:The automatic method introduced in this study is highly reproducible and objective.Because it requires no manual intervention,it may be useful for processing large datasets produced in clinical applications.

Protective effects of tilapia(Oreochromis niloticus)skin gelatin hydrolysates on osteoporosis rats induced by retinoic acid

Tilapia skin gelatin hydrolysates(TSGH)were obtained by complex protease hydrolysis.The amino acid sequences of 50 peptides in TSGH were identified,and most of these peptides were found to contain the-Gly-Pro-sequence.The osteoporosis(OP)rat model induced by retinoic acid was prepared,and the effects of different doses of TSGH on OP in vivo were evaluated.Serum calcium(Ca)and phosphate(P),alkaline phosphatase activity,and osteocalcin levels in OP rats were regulated by TSGH.The bone length,dry weight index,maximum load,and Ca content of OP rats significantly increased by treatment TSGH in a dosedependent manner.Micro-CT images of the femurs and tibias of the rats indicated that the bone mineral density,cortical bone thickness,and cortical/trabecular bone area ratios were recovered and that OP symptoms were improved.Tartrate-resistant acid phosphate and hematoxylin-eosin staining showed that osteoclast numbers and histomorphological changes in the femurs in OP rats could be recovered by TSGH.

Lodging-Resistance Breeding of Platycodon grandiflorus Using Distant Hybridization

The distant hybridization was used in lodging-resistance breeding of Platycodon grandiflorus. The parents were Platycodon grandiflorus (♀) and Campanula medium (♂). 187 seeds of F1 were harvested by using the inter-generic hybridization in 2009 and 2010, 2 repeat, and 88 normal plants were obtained. The characteristics of leaves, stems and branches were the same as female for F1 generation, F2 generation, backcross generation and S1 generation, and there were some different characteristics with female which were flower colors, branching habit and plant height. A lodging-resistance plant was selected in F1, which was about 75 cm high, deep pink flower color and developed lateral branches. The DNA groups of each generation were separated by 1% agarose gel electrophoresis and there were not significant differences. Among the each generation many flower colors and forms were obtained.

Cold-Resistant Breeding of <i>Oenothera speciosa</i>Using Silico Ion Implantation

Oenothera speciosa, belonging to thermophilous plant, cannot overwinter in Beijing. To enhance the overwintering rate of Oenothera speciosa, the seeds were treated through silico ion implantation (SII), with five various fluence ranges (1 × 109 - 1 × 1011 ions/cm2) of 40 MeV and four various fluence ranges (1 × 1010 - 5 × 1011 ions/cm2) of 35 MeV, respectively. M1 generations of various SII-treated Oenothera speciosa lines can overwinter, and the highest overwinter rate (41.3%) was observed in Oenothera speciosa lines treated with 35 MeV and fluence 5 × 1010 ions/cm2. M2 and M3 generations of all treated lines were able to overwinter smoothly. The results indicated that SII treatment can enhance the cold-resistance of Oenothera speciosa heritably. Furthermore, physiological indexes including relative electrical conductivity, MDA contents and proline contents of SII-treated Oenothera speciosa pot seedlings were detected after low temperature stress. The results revealed that relative electrical conductivities and MDA contents of M1, M2 and M3 generations of SII-treated Oenothera speciosa plants were lower than that of control, whereas the proline contents were higher than control in the &#455&#176C cold stress. Taken together, the cold resistance of SII-treated Oenothera speciosa plants was improved, which made it possible to be used as a perennial flower in landscaping in Beijing.

基于第一性原理的β-C_(3)N_(2)笼中原子嵌入引起的超硬磁性新材料设计

基于第一性原理计算,我们通过将客体原子嵌入β-C_(3)N_(2)笼状结构的内在空腔中,预测了机械超硬和可控磁性的共存.以氢掺杂(H@β-C_(3)N_(2))和氟掺杂(F@β-C_(3)N_(2))为例,我们的研究表明两种掺杂构型是稳定的,并发现它们分别属于反铁磁半导体和铁磁半金属.这些有趣的磁相变源于它们在费米能级周围独特的能带结构,并可通过具有半填充占据的3D Hubbard模型和Stoner模型很好地解释.此外,H@β-C_(3)N_(2)和F@β-C_(3)N_(2)的高维氏硬度(49.0和48.2 GPa)表明它们具有笼状超硬材料特征.因此,氢和氟在β-C_(3)N_(2)笼中的掺杂分别产生了一种新型的超硬反铁磁半导体和超硬铁磁半金属,这些材料在极端条件下具有潜在的应用前景.我们的工作为设计具有优异机械性能和磁性的新型高性能多功能材料提供了一种有效的策略,这可能会为超硬材料未来在自旋电子学的应用提供理论依据.

Development and validation of a preoperative prediction model for all-cause mortality in patients following abdominal aortic aneurysm repair

To the Editor:Abdominal aortic aneurysm(AAA)is a life-threatening vascular disease.Surgical intervention is typically recommended when the maximum AAA diameter reaches a threshold of 5.5cm for men and 5.0cm for women,or when an AAA experiences a rapid expansion of greater than 1.0cm/year.[1]Survival after AAA repair is inuenced by various factors,and the identication of independent prognostic factors and the development of accurate prediction models are crucial for optimal treatment planning,counseling,and postoperative follow-up.Although several scoring systems with varying degrees of accuracy have been developed to predict the risk of mortality after intervention for patients with ruptured AAA.

Toxic effects of 1-methyl-3-octylimidazolium bromide on the wheat seedlings

The toxic effects of 1-methyl-3-octylimidazolium bromide （[C8mim]Br） on wheat seedlings were evaluated. Wheat seedlings were cultivated in aqueous solution with [C8mim]Br at different concentrations （0, 1, 2, 4, 6, 8 mg/L）. The contents of photosynthetic pigment and proline, peroxidation of membrane lipid, and activities of antioxidation enzymes （superoxide dismutase, catalase, peroxidase and ascorbate peroxidase） in leaves were measured on day 7 after treatment with [C8mim]Br. The results showed that [C8mim]Br significantly decreased the contents of photosynthetic pigments, activities of antioxidant enzymes in the wheat leaves and in dry weight of seedlings, while increased the proline content and membrane lipid peroxidation. The results suggested that [C8mim]Br can inhibit photosynthesis and lead to oxidative stress to wheat seedlings.