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The demand for larger passenger capacity and more entertainment facilities has led to the rapid growth of the cruise tourism market. The superstructure of cruise ships is designed to be plumper, with numerous decks and complex structural forms. To control the weight and the center of gravity, the bending stiffness of the superstructure is always designed to be weaker than that of the main hull, resulting in a stiffness step. Currently, there is no satisfactory method to accurately estimate the influence of the stiffness step between the main hull and superstructure on the structural response of cruise ships. In the present research, an experimental analysis is conducted to investigate the stiffness step between the main hull and superstructure of a typical cruise ship. By comparing the longitudinal stress distribution characteristics with and without the stiffness step with the theoretical results, the influence of the stiffness step on the longitudinal strength is investigated. Furthermore, the maximum stress and the bending efficiency of the superstructure are also discussed. The present research is of reference significance for the structural safety and reliability design of cruise ships.

The present study focuses on buckling and collapse behaviors of cracked steel panel by accounting for the crack opening/closure. A rectangular panel with a transverse through crack to the loading direction is selected to better understand the typical mechanical characteristics of a panel subjected to a sequence of tensile to compressive loading. When a tensile load is applied to the cracked panel, a through crack gradually opened and yielding occurs around the crack tip. When a compressive load is applied after the tensile load, the crack gradually closed and elastic/elasto-plastic buckling occur. A shell-solid mixed finite element (FE) model is adopted to effectively analyze the crack opening/closure. Shell FEs are employed in the rectangular panel (shell model), while solid FEs are partially adopted around the crack (solid model). Double nodes and contact condition are imposed on the crack face. The shell and solid models are joined together with a rigid body element (RBE). The buckling and collapse behaviors of the panel models under a sequence of tensile to compressive loading is critically examined, as well as its local behavior, i.e., crack opening displacement (COD) varying displacement amplitude, panel aspect ratio and panel thickness. The results show that the crack opening/closure strongly affect the buckling and collapse behaviors of the cracked panel.

The external loads and structural ultimate strength are two important aspects for the safety of ship hull girder. It may collapse in case the structural capacity is less than the external forces in extreme seas. In the present research, progressive collapse test is performed to investigate the collapse mechanism of ship structure in waves. External load with time history and corresponding structural collapse behavior are measured and discussed to demonstrate the interaction of fluid and structures.

BackgroundSupercutaneous locking plate (SLP) has been tried to treat tibia fracture with certain success, but some inevitable problems: such as insufficient stability, screw tract inflammation and the impingement on knee and ankle joint movement have got in the way of its application. Few literature have focused on the possible solution for the above-mentioned problems, and few reports have tried the method of two SLPs.Methods43 patients received two SLPs as final treatment and 39 finished follow-up. 25 patients were open fracture and 18 of them needed skin graft, 11 patients had severe skin contusion, 3 patients had nearby soft tissue infection. Moore and Dahl pin site classification was used to record screw tract inflammation. Lysholm knee score and Kofoed ankle score were used to assess the knee and ankle function. An FE tibial fracture model was reconstructed to analyze the stiffness of different fixation.Results38 of 39 patients had bony union, the other one had clinical union. No bone infection or plate breakage was found while two screws were found broken at the rod-cap junction. FE analysis showed the structure axial stiffness (N/mm2) decreased with the plate-bone distance increased for one SLP, but two SLPs could greatly increase axial stiffness with the stiffness of SLP-2/4(364) was stronger than that of SLP-0(360.6). Function of knee and ankle was well accepted by most patients even with two plates on tibia, the lysholm knee score and kofoed ankle score was 78.9士5.0 and 72.3士7.0 respectively for two plates. When the number of plate decreased, lysholm knee score and kofoed ankle score further increased significantly. All patients had screw site inflammation: grade 2 in 25 cases; grade 3 in 14 cases. ConclusionsTwo SLPs can provide enough strength for bone union. Screw tract inflammation is inevitable, but infection could be foreseen and controlled. The impingement of SLP on knee and ankle joint movement is limited. Two SLPs maybe a good supplement treatment for complex tibia fracture.

Underwater explosion (UNDEX) is one of the major threats to the vitality and sustained combat ability of the warship in the marine military confrontation with both attack and defense. Although there have been plenty of researches focusing on the UNDEX load and its damage effect, the failure mechanism of the structure under the combined UNDEX and wave induced load, especially in extreme sea conditions, is still unrevealed. In this paper, a method for calculating the dynamic response of the hull girder subjected to the combined UNDEX and wave induced load is proposed, in which the acoustic–structure interaction method was employed for determining the UNDEX load, and the wave induced response of hull girder was derived by using hydrodynamic to structure (HTS) calculation procedure. The synergistic effect of the combination of different levels of wave induced load and the underwater explosion was analyzed. It is found that the hull girder is more dangerous under the combined UNDEX and wave induced load, especially in the severe wave level. The damage severity of the hull girder will be underestimated without considering the synergistic effect of the combined loads.

The dynamic buckling of the main deck grillage would result in the total collapse of the ship hull subjected to a far-filed underwater explosion. This dynamic buckling is mainly due to the dynamic moment of the ship hull when the ship hull experiences a sudden movement under impact load from the explosion. In order to investigate the ultimate strength of a typical deck grillage under quasi-static and dynamic in-plane compressive load, a structure model, in which the real constrained condition of the deck grillage was taken into consideration, was designed and manufactured. The quasi-static ultimate strength and damage mode of the deck grillage under in-plane compressive load was experimentally investigated. The Finite Element Method (FEM) was employed to predict the ultimate strength of the deck grillage subjected to quasi-static in-plane compressive load, and was validated by comparing the results from experimental tests and numerical simulations. In addition, the numerical simulations of dynamic buckling of the same model under in-plane impact load was performed, in which the influences of the load amplitude and the frequency of dynamic impact load, as well as the initial stress and deflection induced by wave load on the ultimate strength and failure mode were investigated. The results show that the dynamic buckling mode is quite different from the failure mode of the structure subjected to quasi-static in-plane compressive load. The displacements of deck edge in the vertical direction and the axial displacements are getting larger with the decrease of impact frequency. Besides, it is found that the dynamic buckling strength roughly linearly decreased with the increase of initial proportion of the static ultimate strength P0. The conclusions drawn from the researches of this paper would help better designing of the ship structure under impact loads.

We consider the problem of seeking communities in directed networks. The common approach to this problem has been to simply ignore directions of edges and use algorithms developed for community detection in undirected networks, but this approach discards potentially indispensable information involved in the directions of edges. Here, we introduce an index for node dissimilarity in directed networks in the perspective of dynamics, which are driven by a novel parameter-free signal copying model, to incorporate information contained in the directions of edges. Our dissimilarity index gives a natural fusion between the local and global viewpoints of topological structure of directed networks. Thereby, we apply our index to uncover community structure in directed networks and conduct extensive experiments on synthetic and real-world ones. The results demonstrate that our method outperforms state-of-the-art methods.

A single wave of extreme height can damage ship structures in the ocean by generating buckling midship, thus destabilizing the ship girder and causing rupture. The probability of such an extreme wave is low in reality. On the one hand, it is very costly to recreate a real ship test for the study of extreme wave conditions. On the other hand, it is difficult to carry out tests on a scale model in tank waves, because such waves are too small to damage the ship model. In this paper, a hydroelasto-buckling experiment is performed on a ship model to study the dynamic ultimate strength of the ship and dynamic course of collapse of the structure. Thus far, no method of simulation has been proposed to study this problem because the dynamic ultimate strength of the ship involves strong coupling between the nonlinearity in the ship structure and waves. Here, a hydroelasto-buckling ship model is first designed, and a test programme is determined. A buckling hinge that can collapse under the load of the tank wave is used to connect two ship girders with a hinge joint. Then, a number of single tank waves are generated by changing their wave patterns to simulate an extreme ocean wave. The dynamic rotation angle, bottom water press and acceleration at midship are measured in the experiment. Importantly, the relationship between structural response and wave patterns is analyzed. The structural response involves encountering the VBM/rotation deformation induced by the wave load and whipping the VBM/rotation deformation induced by natural structural oscillations. It is found that the ultimate strength of the ship girder can be generated by both encountering waves and the structural flutter response caused by changing wave height. Lastly, the midship water pressure and acceleration are also analyzed to discuss the influence of a large deformation of the ship structure on the fluid load. Some conclusions are presented in the paper.

The changes in sap flow of Salix psammophila growing on a gentle slope (lower slope, P1), a middle slope (P2), and an upper slope (P3), and the response of sap flow to meteorological factors at the different slope positions were studied using the continuous and synchronized observations, the instrument were wrapped stem flowmeter EMS 62 sap-flow heat-balance-based system and the LSI-LASTEM automatic weather station. The results revealed that the soil moisture content was the highest and the growth conditions of Salix psammophila were the best at P1, followed by P2. At P3, however, although good apical dominance was observed, the proportion of dead branches was the highest. Furthermore, the daily variation patterns of sap flow on the three slopes presented as multi-peak bell-shaped curves. The daily accumulation changes in sap flow showed a trend of P1 > P3 > P2, and within the same diameter range, the sap flow at P1 was significantly different from that at P2 and P3, whereas the sap flow at P2 and P3 did not vary significantly. All the three slopes showed a significant and positive correlation with photosynthetically active radiation, atmospheric temperature, and vapor pressure difference, and a significant and negative correlation with relative humidity; however, the degrees of correlation varied slightly. The stepwise regression analysis showed that, at different slopes, different variables were selected for different branch diameters, but photosynthetically active radiation and atmospheric temperature played dominant roles on all slopes. This study reveals the sap flow pattern of Salix psammophila on different slopes and its response mechanism to meteorological factors, which was essential for understanding the restoration ability, physiological adaptability, and ecosystem stability of Salix psammophila communities.

We investigate the explosive synchronization in networks with core-periphery structure. The effects of different patterns of core-periphery networks on explosive synchronization are studied by altering network structural parameters. With the variation of two core-periphery structural parameters, the relative connection strength between core and peripheral nodes, and the relative connection strength among peripheral nodes, we find distinct roles played by structural parameters in the path toward explosive synchronization. Our results show that the order parameter of periphery is closer to that of the core in the synchronization phase with the increment of connections between core and peripheral nodes. In addition, we find that sparser the connections among peripheral nodes are, the easier the whole dynamic network is to reach explosive synchronization. We also discover that if the number of connections between core and periphery scales vary sublinearly with the network size, there exists a novel two-jump behavior of the order parameter of the whole network. Moreover, as the level of the sublinearity increases, the order parameter starts to oscillate in a decaying manner, rather than being increasing monotonically and slowly as in the case of normal explosive synchronization when the coupling strength exceeds a critical threshold. Hence in this regime, it becomes increasingly difficult for the network to maintain stable explosive synchronization even though the underlying network topology is connected.

Wave load is one of the main external loads for semi-submersible platform, which is usually calculated by design wave method. In the present research, three design wave methods are investigated and compared on design wave parameters determination of semi-submersible platforms, i.e., the deterministic design wave method, stochastic design wave method and long-term prediction design wave method. Moreover, the specified calculation methods and the detailed wave load computation procedure are summarized considering the load characteristics of global hydrodynamic response. Finally, a semi-submersible platform is regarded as objective and the design wave results of three design wave methods are compared and analyzed. The fundamental research can provide reference for rational selection of wave loads calculation method.

The combination damage induced by mechanical interference, in reality, is more likely to happen. In this paper, numerical models on pipes with combined dent and metal loss in terms of a notch are developed and validated through tests (diameter-to-thickness ratio D / t of test pipes around 21), capable of predicting the residual ultimate strength of pipes in terms of bending moment ( M c r ) and critical curvature ( κ c r ). The effect of residual stress is explored, assuming a linear distribution in the pipe hoop direction. Investigations of damaged pipes with different D / t (15–50) are carried out. Through changing damage parameters in the combinations, i.e. dent depth ( d d ) or metal loss depth ( d m ), the corresponding effects of damage are clarified. Results show that the combined dent and notch damage is a more severe type of damage on pipe strength compared with other damage types (excluding fracture). The dent in combined damage plays a more dominant role on the pipe residual strength. Empirical formulas are proposed to predict residual ultimate strength of damaged metallic pipes ( D / t around 21) with combined dent and metal loss under bending moment, which can be used for practical purposes. The application domain can be expanded to pipes with D / t up to 30 based on simulations.

Numerical investigation is conducted in this paper on both intact and dented seamless metallic pipelines (diameter-to-thickness ratio D/t around 21), deploying nonlinear finite element method (FEM). A full numerical model is developed, capable of predicting the residual ultimate strength of pipes in terms of bending capacity (Mcr) and critical curvature (κcr). The simulation results are validated through test results by using the measured material properties and specimen geometry. An extensive parametric investigation is conducted on the influences of material anisotropy, initial imperfection, friction of the test set-up and dent parameters. It is found that the structural response is quite sensitive to the frictions that have been introduced by the test configuration. For a pipe with a considerable dent size, the effect of manufacturing induced initial imperfection is insignificant and can be neglected in the FEM simulation. The material yield stress in the pipe longitudinal direction dominates the bending capacity of structures. In the end, formulas are proposed to predict the residual ultimate strength of dented metallic pipes under pure bending moment, which can be used for practical purposes. A satisfying fit is obtained through the comparison between the formulas and FEM methods.

To ensure the safety of navigating ship, working loads and structural load-carrying capacity are two important aspects. In the present paper, a total simulation system combing load calculation and structural collapse analysis is applied to simulate progressive collapse behaviour of a single-hull Kamsarmax type bulk carrier. A three dimensional singularity distribution method is adopted to calculate pressure distribution with time history. A mixed structural model, collapse part simulated by ISUM elements and remaining part by elastic FEM elements with relative coarse mesh, is proposed for collapse analysis. Progressive collapse behaviour obtained by ISUM is good agreement with that by nonlinear software package, MARC. However, the calculation time of ISUM analysis is about 1/70 of MARC analysis. The applicability to structure system, high accuracy and sufficient efficiency of ISUM had been demonstrated.

The ultimate strength of metallic pipelines will be inevitably affected when they have suffered from structural damage after mechanical interference. The present experiments aim to investigate the residual ultimate bending strength of metallic pipes with structural damage based on large-scale pipe tests. Artificial damage, such as a dent, metal loss, a crack, and combinations thereof, is introduced to the pipe surface in advance. Four-point bending tests are performed to investigate the structural behavior of metallic pipes in terms of bending moment–curvature diagrams, failure modes, bending capacity, and critical bending curvatures. Test results show that the occurrence of structural damage on the pipe compression side reduces the bending capacity significantly. Only a slight effect has been observed for pipes with damage on the tensile side as long as no fracture failure appears. The possible causes that have introduced experimental errors are presented and discussed. The test data obtained in this paper can be used to further quantify damage effects on bending capacity of seamless pipes with similar D/t ratios. The comparison results in this paper can facilitate the structural integrity design as well as the maintenance of damaged pipes when mechanical interference happens during the service life of pipelines.

Essential hypertension (EH) has become a major chronic disease around the world. To build a risk-predicting model for EH can help to interpose people's lifestyle and dietary habit to decrease the risk of getting EH. In this study, we constructed a EH risk-predicting model considering both environmental and genetic factors with support vector machine (SVM). The data were collected through Epidemiological investigation questionnaire from Beijing Chinese Han population. After data cleaning, we finally selected 9 environmental factors and 12 genetic factors to construct the predicting model based on 1200 samples, including 559 essential hypertension patients and 641 controls. Using radial basis kernel function, predictive accuracy via SVM with function with only environmental factor and only genetic factor were 72.8 and 54.4%, respectively; after considering both environmental and genetic factor the accuracy improved to 76.3%. Using the model via SVM with Laplacian function, the accuracy with only environmental factor and only genetic factor were 76.9 and 57.7%, respectively; after combining environmental and genetic factor, the accuracy improved to 80.1%. The predictive accuracy of SVM model constructed based on Laplacian function was higher than radial basis kernel function, as well as sensitivity and specificity, which were 63.3 and 86.7%, respectively. In conclusion, the model based on SVM with Laplacian kernel function had better performance in predicting risk of hypertension. And SVM model considering both environmental and genetic factors had better performance than the model with environmental or genetic factors only.

Recent progress in the development and application of the ISUM plate element is highlighted with a particular focus on its application to the progressive collapse analysis of a ship hull structure. The plate element is characterized by idealized shape functions for defection based on buckling collapse mode and a simple procedure for element formulation similar to that for standard displacement-based finite elements. The formulation of the plate element under in-plane loads is presented, and then the plate element and the plate-stiffener combination model are applied to the progressive collapse analysis of a hull-girder cross section and double bottom structure. The development of a total system for motion/collapse analysis of a whole ship in waves is also presented. The effectiveness of these ISUM models is demonstrated.

A long-term (20 months) bulk litter decomposition experiment was conducted in a subtropical plantation in southern China in order to test the hypothesis that stable isotope discrimination occurs during litter decomposition and that litter decomposition increases concentrations of nutrients and organic matter in soil. This was achieved by a litter bag technique. Carbon (C), nitrogen (N) and phosphorus (P) concentrations in the remaining litter as well as delta(13)C and delta(15)N during the experimental period were measured. Meanwhile, organic C, alkali-soluble N and available P concentrations were determined in the soils beneath litter bags and in the soils at the control plots. The dry mass remaining (as % of the initial mass) during litter decomposition exponentially declined (y = 0.9362 e(-0.0365x) , R (2) = 0.93, P < 0.0001), but total C in the remaining litter did not decrease significantly with decomposition process during a 20-month period. By comparison, total N in the remaining litter significantly increased from 5.8 +/- A 1.7 g kg(-1) dw litter in the first month to 10.1 +/- A 1.4 g kg(-1) dw litter in the 20th month. During the decomposition, delta(13)C values of the remaining litter showed an insignificant enrichment, while delta(15)N signatures exhibited a different pattern. It significantly depleted (15)N (y = -0.66x + 0.82, R (2) = 0.57, P < 0.0001) during the initial 7 months while showing (15)N enrichments in the remaining 13 months (y = 0.10x - 4.23, R (2) = 0.32, P < 0.0001). Statistically, litter decomposition has little impact on concentrations of soil organic C and alkali-soluble N and available P in the top soil. This indicates that nutrient return to the topsoil through litter decomposition is limited and that C cycling decoupled from N cycling during decomposition in this subtropical plantation in southern China.

In this work, a novel method was developed to distinguish nucleosome DNA and linker DNA based on increment of diversity combined with quadratic discriminant analysis (IDQD), using k-mer frequency of nucleotides in genome. When used to predict DNA potential for forming nucleosomes, the model achieved a high accuracy of 94.94%, 77.60%, and 86.81%, respectively, for Saccharomyces cerevisiae, Homo sapiens, and Drosophila melanogaster. The area under the receiver operator characteristics curve of our classifier was 0.982 for S. cerevisiae. Our results indicate that DNA sequence preference is critical for nucleosome formation potential and is likely conserved across eukaryotes. The model successfully identified nucleosome-enriched or nucleosome-depleted regions in S. cerevisiae genome, suggesting nucleosome positioning depends on DNA sequence preference. Thus, IDQD classifier is useful for predicting nucleosome positioning.

Carbon fluxes were measured using a static chamber technique in an alpine steppe in the Qinghai-Tibet Plateau from July 2000 to July 2001. It was shown that carbon emissions decreased in autumn and increased in spring of the next year, with higher values in growth seasons than in winters. An exponential correlation (E(carbon) = 0.22(exp(0.09T) + ln(0.31P + 1)), R(2) = 0.77, P < 0.001) was shown between carbon emissions and environmental factors such as temperature (T) and precipitation (P). Using the daily temperature (T) and total precipitation (R), annual carbon emission from soil to the atmosphere was estimated to be 79.6 g C/m(2), 46% of which was emitted by microbial respiration. Considering an average net primary production of 92.5 g C/m(2) per year within the 2 year experiment, alpine steppes can take up 55.9 g CO(2)-C/m(2) per year. This indicates that alpine steppes are a distinct carbon sink, although this carbon reservoir was quite small.

Genome-wide association studies (GWASs) have been playing an important role on human complex diseases. Generally speaking, GWAS tries to detect the relationship between genome-wide genetic variants and measurable traits in the population level. Although fruitful, array-based GWASs still exist some problems, for example, the so-called missing heritability--significantly associated SNPs can only explain a small part of phenotypic variation. Other problems include that, in some traits, significantly associated SNPs in one study are hard to be repeated by other studies; and that the functions of significantly associated SNPs are often difficult to interpret. High-throughput sequencing, also known as next-generation sequencing (NGS), could be one of the most promising technologies to solve those problems by quickly producing accurate variations in a high-throughput way. NGS-based GWASs (NGS-GWAS), to some extent, provide a better solution compared with traditional array-based GWASs. We systematically review the strategies and methods for NGS-GWASs, pick out the most feasible and efficient strategies and methods for NGS-GWASs, and discuss their applications in personalized medicine.