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This study uses the critical incident technique to collect and analyze incidents of service failure and success involving a logistics sharing service in which the service providers are individuals. The authors also explore the key factors that affect customer satisfaction, along with the official and ideal recovery strategies. Data is based on interviews with 35 business users in Taiwan in 2017. A card sorting exercise is employed to classify the collected incidents and strategies into categories. The results show that the determinants of success and failure in logistics sharing services include drivers, platform operation, the matching system, and communication. Compensation is the most effective recovery strategy, whereas doing nothing is the least effective. Suggestions based on our results can help managers of the sharing economy to avoid or recover from failures and attain success.

This study evaluated the fatigue strengthening of the foremost transverse hatch coaming stays of 6 sister container vessels of 2650 TEU capacity that suffered fatigue cracking after 1.0 year operation on a North Pacific route. For that, a simplified method was proposed to validate the fatigue strengthening by providing a target hot spot stress reduction factor as a function of the ship lifetime at the crack occurrence. Afterwards, further seakeeping and structural analyses enabled conducting the spectral fatigue analyses of the considered stays’ original and strengthened designs and, by then, to validate the fatigue strengthening of the stays and the simplified approach. The fatigue driving loads, as well as the effect of the long-term operational profiles uncertainties on the fatigue were also discussed on the basis of the spectral fatigue analyses. Finally, crack growth analyses confirmed the criticality of the examined stays with regards to rapid fatigue cracking when the fatigue damage is not properly considered at the design stage.

Background Desmoid tumors (DTs) are rare mesenchymal lesions that can recur repeatedly. When it is feasible, DTs are surgically resected; however, this often results in high recurrence rates. Recently, treatment with PF-03084014, a potent γ-secretase inhibitor, has been shown to have antitumor activity in several tumor types by affecting the WNT/β-catenin pathway. Consequently, Notch pathway inhibition by PF-03084014 might be a promising approach for DT treatment. Methods The expression of Notch pathway components was analyzed in DT tissues and cell strains with immunohistochemistry and Western blotting, respectively. A panel of DT cell strains was exposed to PF-03084014 and evaluated for cell proliferation. Antitumor effects were assessed via cell cycle, apoptosis, and migration and invasion analysis. Cells treated with PF-03084014 were characterized with a gene array analysis combined with Ingenuity Pathway Analysis. Results The results showed that Notch pathway components were expressed at different levels in DTs. Hes1 (Hes Family BHLH Transcription Factor 1) was overexpressed in DT tumors versus dermal scar tissue, and PF-03084014 caused significant decreases in Notch intracellular domain and Hes1 expression in DT cell strains. PF-03084014 decreased DT cell migration and invasion and also caused cell growth inhibition in DT cell strains, most likely through cell cycle arrest. Gene array analysis combined with Ingenuity Pathway Analysis showed that Wnt1-inducible signaling pathway protein 2 possibly regulated Notch and WNT pathways after treatment with PF-03084014 through integrin. Conclusion Our findings suggest that the Notch pathway is an important DT therapeutic target. Furthermore, PF-03084014 has significant antitumor activity against DTs, and it may be an alternative strategy for DT treatment.

Structural analysis of FRP wind turbine blades must take into account phenomena associated with aerodynamics as well as fluid–structure coupling, because aerodynamic loading causes blades to bend mostly in the flapwise direction, and simultaneously causes foil sections to rotate to create new fluid fields around the foils. This study developed an analytical process for calculating fluid–structure interaction, while considering the effects of aerodynamic pressure and finite element analysis in the design of wind turbine blades. In addition, we calculated turbine power efficiency to evaluate the results of fluid–structure interaction displaying approximately power capacity loss of 17% at a wind speed of 25 m/s, and proposed three feasible improvements to enhance the performance of wind turbines. The presented study provided a comprehensible means by which to interpret changes in the aeroelastic response of blades, and was helpful to modify the original wind turbine model.

A sandwich assembly with core material enhances the bending stiffness of a structure and achieves lightweight requirements. Resin flowing behavior inside a sandwich assembly consisting of fiber layers and a segmented core is more complex than that for a fibrous assembly consisting of only fiber layers. This study presents infusion experiments on sandwich assemblies in the VARTM process, and compares the results to simulations from a 3D sandwich model including circular pipe elements to substitute for core grooves. Using the concepts of equivalent thickness to define the porosity of a sandwich assembly and porous space helps derive permeability trends and predictive equations to simplify permeability calculation. The deck infusing experiment in this study not only proves the permeability rationality of a sandwich assembly, but also provides concepts and suggestions for infusion arrangements. Consequently, the permeant characteristics in the sandwich assembly are applicable to manufacturing sandwich structures with good saturation.

Background Protein transduction domains (PTDs) can be fused to a protein to render it cell-permeable. The delivery efficiencies of PTDs are, however, often poor because PTD-protein conjugates cannot escape from endosomes. A potential solution to this problem consists in adding HA2 analogs to the PTD-protein construct as these peptides can cause endosomal lysis upon acidification of the endosomal lumen. To date, however, the utility of HA2-based PTDs has not been clearly established. Methods We investigate the biophysical and cellular properties of the glutamate-rich HA2 analog E5 fused to the model protein TAT-mCherry. Results E5-TAT-mCherry causes the release of fluorescent dextrans trapped with the protein inside endosomes. Yet, E5-TAT-mCherry itself is not released in the cytosol of cells, indicating that the protein remained trapped inside endosomes even after endosomal lysis takes place. Cytosolic delivery of the protein could be achieved, however, by insertion of a disulfide bond between E5 and its cargo. Conclusions These results show that E5 causes the retention of its fused protein inside endosomes even after lysis takes place. General significance These data establish that HA2 analogs might not be useful PTDs unless cleavable linkers are engineered between PTD and protein cargo.

With experiments, this study discussed the characteristics of composite curvature shells with constrained layered damping (CLD) subjected to low-velocity impact as well as compared the reactions of the curvature shells with/without CLD. In addition to the experiments, this study proposed the quasi-static simulation, which could rapidly obtain the results with different impact velocities and drift masses with the force–displacement curve of static crushing test, to receive the results subjected to low-velocity impact under various impact conditions. The shell specimens were laminated with two stacking sequences collocating two different drift masses and impact velocities. The experiment of low-velocity impact applied Dynatup-GRC8250 and IDA system to measure the impact force at various time-points in the process of impact and, with the conservation of energy, changes of velocity and strain energy in the impact process could be calculated with the initial velocity of the impact. Finally, the quasi-static simulations were compared with the experiments to verify the accuracy of simulations, and results were found satisfactory.

Utilizing a sandwich structure enables FRP assembly to increase bending stiffness and achieve lightweight requirements. Core surfaces are often cut and infused together with fiber laminates in the VARTM process. Nevertheless, resin infusion in the sandwich structure differs from pure fibrous laminates because resin flows rapidly in the grooves and then saturates into the laminates. This research performed sandwich structure infusion experiments under the VARTM process, and defined four resin saturation stages inside the sandwich assembly by observing and explaining the nonlinear experimental flowing fronts. This study also discussed the race-tracking phenomenon of the sandwich structure in detail. This research executed infusion simulations in the 3D sandwich model, including fiber layers and grooves replaced by the circular pipe elements, to compare with the experimental results. Realization of the permeant characteristics in the sandwich structure establishes a base to ensure complete saturation and to analyze the manufacture of large sandwich structures.

This paper demonstrates the experimental result of changeable pitch propellers in composite material. The use of this composite material is to apply its characteristic of bend-twist coupling; this characteristic is applied to better performance design requirements of the propeller. Two stacking sequences are considered: the first one is a quasi isotropic sequence, while the second one is an optimum sequence obtained using a genetic algorithm. Experiments are designed considering two original propellers manufactured by the first and the second stacking sequence, respectively, and a pre-deformed propeller with the second sequence. Experimental results correspond to the same trend as the calculations and confirm the method of optimization.

This investigation presents a quasi-static simulation method that adopts energy conservation and the results from the static crush to simulate the impact behavior of carbon-epoxy composite laminate plates. These plates consist of adhered visco-elastic material, and formed constrained layered damped (CLD) components. The damping force is considered in the quasi-static simulation. Comparison with experimental results indicates that the proposed method yields accurate results and produces significant saving in computing resources.

Plate and shell specimens were formed from carbon–epoxy prepregs. Then, attaching 3 M damping foil SJ-2552 to specimens formed constrained layered damped (CLD) components with sandwich-like structures. A steel indentor was used to compress the plate and shell specimens until they completely collapsed. The crushing strength of the CLD components is examined experimentally, and the finite element software ABAQUS is used to simulate the experimental crushing behavior using the user-defined material (UMAT) subroutine. UMAT allows users to define the progressive stiffness modification and analyze the fracturing of composite components. The ultimate strengths of the CLD components are accurately estimated using the UMAT, and the failure observed in the experiments closely corresponds to that in the numerical simulations.

When fiber-reinforced plastic (FRP) crafts sail at high speed, very large slamming forces impact the bottom structures of crafts. Therefore, the capacity to resist these forces is an important factor when designing crafts. In the past, the instability and complexity of material properties in failure analysis, in addition to the difficulties in conducting the laminate failure experiments due to water impact, resulted in few studies investigating the failure progress of FRP laminates subjected to water impact. This study presents a novel impulsive water-pressure failure experimental system that combines a hydraulic system with a water-pressure failure experimental fixture used in previous work, to generate impulsive water pressure. Using this system, the FRP laminates are deformed and damaged under water impact. In numerical analysis, the finite element software ABAQUS and user subroutine user-defined field (USDFLD) are utilized to calculate the strain field of laminates as a basis of failure evaluation and stiffness degradation of a structure after specifying failure criteria and stiffness modification curve obtained from material tests for different materials. By comparison with experimental data, the numerical model can be validated, regardless of whether the impulsive water loads are sufficiently small or large to cause structure failure. Consequently, based on the results of this study, the abilities of analyzing the dynamic failure progress under out-of-plane impulsive water pressure and the corresponding experimental systems can be well established. Furthermore, the capacity of FRP laminates in resisting water pressure can also be elucidated.

Gastric cancer is a leading cause of death worldwide, and patients have an overall 5-year survival rate of less than 10%. Using quantitative proteomic techniques together with microarray chips, we have established comprehensive proteome and transcriptome profiles of the metastatic gastric cancer TMC-1 cells and the noninvasive gastric cancer SC-M1 cell. Our qualitative protein profiling strategy offers the first comprehensive analysis of the gastric cancer cell proteome, identifying 926 and 909 proteins from SC-M1 and TMC-1 cells, respectively. Cleavable isotope-coded affinity tagging analysis allows quantitation of a total of 559 proteins (with a protein false-positive rate of0.005), and 240 proteins were differentially expressed (1.3-fold) between the SC-M1 and TMC-1 cells. We identified numerous proteins not previously associated with gastric cancer. Notably, a large subset of differentially expressed proteins was associated with tumor metastasis, including proteins functioning in cell-cell and cell-extracellular matrix (cell-ECM) adhesion, cell motility, proliferation, and tumor immunity. Gene expression profiling by DNA microarray revealed differential expression (of2-fold) of about 1000 genes. The weak correlation observed between protein and mRNA profiles highlights the important complementarities of DNA microarray and proteomics approaches. These comparative data enabled us to map the disease-perturbed cell-cell and cell-ECM adhesion and Rho GTPase-mediated cytoskeletal pathways. Further validation of a subset of genes suggests the potential use of vimentin and galectin 1 as markers for metastasis. We demonstrate that combining proteomic and genomic approaches not only provides a rapid, robust, and sensitive platform to elucidate the molecular mechanisms underlying gastric cancer metastasis but also may identify candidate diagnostic markers and therapeutic targets.

The material and ply angles of a fiber-reinforced plastic (FRP) rotor blade of a helicopter are optimized using a genetic algorithm (GA) with local search. The variation of the structural stiffness with material and ply angle is investigated. The aim of the optimization is to find an optimal stacking sequence that minimizes twist deformation. An optimum rotor blade is obtained using the ply angles as variables; failure, natural frequency, and minimum moment of inertia are used to constrain the optimization. The GA is employed as an optimization tool. A simplified local search is implemented in the final stage of optimization to reduce the searching time.

This study examines the progressive failure of marine glass fiberreinforced plastic (GFRP) laminates subjected to out-of-plane water pressure. First, experimental data concerning laminates that consist of a single type of fiber are used to establish the finite element model by separating the section into fiber layers and matrix layers. After a suitable failure criterion has been specified and the stiffness modification factor of different materials obtained experimentally, a numerical model is used to simulate the failure behavior of marine GFRP laminates. This numerical model is then applied to analyze the failure of GFRP ship bottom structures under water pressure. The water pressure failure experiment is designed to verify the numerical results. The experimental system includes a watertight cabin, which comprises the wall of the fixture, the specimen, and a movable piston, filled with water. Then, the water pressure is increased by moving the piston to compress the water-sealed zone, until the specimen reaches ultimate failure. After the numerical model has been validated, the abilities of testing and analyzing the failure behavior of laminates under static water pressure are established. More information is presented about the capacity to resist out-of-plane water pressure, the proper use of the material, and improving the efficiency of the design.

This work investigates the impact behavior of carbon-epoxy composite-laminated shells with three different curvatures. For the low-velocity impact cases, a quasi-static method is introduced to reduce the need for dynamic approaches. The static crushing information (force-displacement data) of the shell is critical to the quasi-static simulation. Based on the crushing data extracted from experiments or numerical simulations, numerous dynamic impact results for distinct impactor masses and velocities can be obtained immediately from a single static result, as long as these impacts are classified as low-velocity conditions. Static experiments and simulations are always more effective than dynamic ones. This investigation concludes that the quasi-static method delivers excellent exactitude, provided the static force-displacement data, the dominator, are accurately acquired.

Interest in the application of genetic algorithms (GA) to the stacking sequence of composite laminates has grown in recent years. However, the huge calculation time of GA is a major problem for designers. In this study, a local improvement is inserted into a standard GA, and the real calculation, by finite element analysis (FEA) for example, required in the local search is replaced by a regression model. Accordingly, the improved GA converges much sooner than a standard GA and the calculation time is greatly reduced. The regression analysis applies chosen trigonometric functions as base functions, and estimates objective function values accurately using only few sample points. The GA with local improvement is then applied to a sandwich plate and composite propeller, the amount of calculation is reduced by over half.

The crush behavior of carbon-epoxy composite laminated shells with three different curvatures is investigated. The FEM package ABAQUS and the user-defined material subroutine (UMAT) based on the concept of progressive stiffness degradation were employed to simulate crushing until the specimens totally collapsed. The 2-D delamination propagation proposed by Davies et al. is considered to be an additional failure mechanism for some curved shells whose contact crushing forces are large. The ultimate strengths of the shells are accurately predicted by the presented method, and all experimental cases are accurately simulated and explained.

Traditional propellers are made of high-stiffness metal material. They deform only slightly and are usually designed to work at a constant speed, operating at reduced efficiency at other speeds. This research designs a composite propeller that operates over a wider range of speeds. The deformation of propeller is determined by orientating fibers to produce propellers that are more efficient than those made of metal. First, structural and fluid dynamic calculations are performed to determine the deformation, the fluid pressure, and the performance of the propeller. An optimizing genetic algorithm is then used to determine the best stacking sequence of the propeller; however, if the optimal stacking sequence does not outperform a metal propeller, a predeformed design is then used to solve this problem. A smallest pitch stacking sequence is obtained using a genetic algorithm first, and then the propeller is displaced in the opposite direction to form a predeformed propeller. The predeformed propelle...

Some optimization methods have recently been developed to deal with discrete variable problems such as that involving the ply angles and stacking sequence of composite laminates. However, much calculation is still required for the algorithms. A regression equation of the response surface would allow the finite element analysis to be replaced with the regression equation, saving much time in optimization design. The response surface of composite laminated structures is estimated using regression analysis in this study. The information of the surface can be obtained quickly and accurately. Usually, simple polynomials are used as base functions in regression, but the results obtained unsatisfactory in this work. Considering the periodic and directional property of the design variables (ply angles), trigonometric functions are used as base functions in regression and they fit the surface very well. According to the characteristics of ply angle and trigonometric function, the value of variable can be chosen to smoothen the response surface, greatly increasing the accuracy of the regression. This study first establishes the regression procedure, and then applies it to examples of a marine propeller and a rotor wing. The regression is used with a genetic algorithm to search for optimum ply angles in the examples, saving much time while maintaining accuracy.

A steel impactor was used in drop tests to impact composite laminated plates constructed using carbon-epoxy prepregs. The impact force and strain histories were recorded as well. Damage incurred from a low-velocity impact much closely resembled that from static crushing. This investigation creates a user-defined material subroutine (UMAT) of the FEM software ABAQUS, using our method of stiffness progressive modification, such that extreme failure is accurately simulated until the plates are thoroughly crushed. Using the results from the static crush simulation and the aspect of energy conservation, the dynamic impact force given with different impactor masses and initial velocities can be rapidly predicted while making significant savings in computing resources.

Plate specimens were formed from carbon-epoxy prepregs. Thereafter a steel indentor was used to compress the specimens, with the reaction forces were recorded until the plates thoroughly collapsed. The FEM software, ABAQUS, was employed to simulate the crushing of the plates. This investigation creates a user-defined material subroutine to enhance the damage simulation which includes Hashing and Yeh failure criteria. The ultimate strengths of the plates are accurately estimated using the present method of progressive stiffness modification, and the failure observed in experiments closely corresponds to that of the numerical simulations.

Marine glass fiber-reinforced plastic (GFRP) laminates, such as M-R laminates, have various tensile and flexural mechanical properties. This phenomenon holds not only for laminates composed of various fibers, but also for laminates composed of a single type fiber. Therefore, this paper will use both a theoretical and a numerical model to calculate the tensile and flexural Young's moduli, to elucidate the mechanism that explains the discrepancy. According to this, the numerical model of GFRP laminates made from a single type of fiber can be established from the data of material experiments, which are easily performed in the laboratory. The mechanical properties of laminates composed of different types of fibers can then be predicted precisely by this numerical model without further material experiments.

In contrast with previous research focusing on cochlear implants, this study examined the speech performance of hearing aid users with conductive (n = 11), mixed (n = 10), and sensorineural hearing loss (n = 7) and compared it with the speech of hearing control. Speech intelligibility was evaluated by computing the vowel space area defined by the Mandarin Chinese corner vowels /a, u, i/. The acoustic differences between the vowels were assessed using the Euclidean distance. The results revealed that both the conductive and mixed hearing loss groups exhibited a reduced vowel working space, but no significant difference was found between the sensorineural hearing loss and normal hearing groups. An analysis using the Euclidean distance further showed that the compression of vowel space area in conductive hearing loss can be attributed to the substantial lowering of the second formant of /i/. The differences in vowel production between groups are discussed in terms of the occlusion effect and the signal transmission media of various hearing devices.

The present study employs a numerical approach to investigate the post-buckling behavior of laminates connected by rivets. In order to reduce the calculation time, the rivets are replaced with springs, while the stiffness of the springs is induced from the study that analyzes the bending behavior and the interaction between the rivet and the laminate. The finite element software ABAQUS is used to inspect the post-buckling behavior of composite laminates connected by rivets. Several parameters are considered like the stacking sequence, the arrangement of the rivets, and the span between the stiffener. In all these cases, springs can fully present the behavior around the rivets. Finally, the validity of this method is verified by experiment.

A nonlinear finite element code, DELAM3D, with a three-dimensional layered solid element based on the updated Lagragian formulation, is developed to simulate the compressive response of a laminated composite plate with multiple delaminations. An analytical model is established to characterize the mechanical behaviors such as postbuckling, contact of the delaminating interface, delamination growth and fiber-matrix failure. Double cantilever beam (DCB) and end notched flexure (ENF) tests, with T300/976 graphite/epoxy, are performed to verify the energy release rate of the material. Experiments with various crack numbers, sizes, locations and layer orientations have been conducted and compared with the numerical solution. Good agreement is expected.

An activated antiroll tank system design for ship roll reduction was investigated. Considering the dynamics of the ship motion, tank flow, and variable-pitch impeller, a control law is derived based on optimal control and estimation theory. Finally, a series of numerical computations for a 1174 tonne ship without an antiroll tank system, with a passive tank system, and with the proposed activated antiroll tank system is performed. The results show that the proposed activated tank system has superior antiroll properties for free rolling, regular, and irregular sea loads to the passive tank system. In addition, this design has a very low sensitivity to variations in ship and tank dynamics. It shows that the proposed system is reliable and valid for practical use.

The low-velocity impact behavior of sandwich beam subjected to the cylindrical impactor is investigated numerically. Finite element software ABAQUS is used, and maximum stress failure criterion and a modified stiffness degradation method are adopted to analyze the failure behavior of sandwich beam, including initiation of failure, and failure modes. The two failure modes ; shear cracks in foam (Mode I), and crushed in core and damage in the top face sheets right underneath the impactor (Mode II) can be simulated well. At the range of impact velocity on this study, it can be shown that the the dynamic responses of sandwich beam are nearly quasi-static, therefore, the dynamic behavior of sandwich beam such as impact force history can be approximately obtained from static results.

Desmoid tumors (DTs) are rare mesenchymal lesions that can recur repeatedly. When it is feasible, DTs are surgically resected; however, this often results in high recurrence rates. Recently, treatment with PF-03084014, a potent γ-secretase inhibitor, has been shown to have antitumor activity in several tumor types by affecting the WNT/β-catenin pathway. Consequently, Notch pathway inhibition by PF-03084014 might be a promising approach for DT treatment. The expression of Notch pathway components was analyzed in DT tissues and cell strains with immunohistochemistry and Western blotting, respectively. A panel of DT cell strains was exposed to PF-03084014 and evaluated for cell proliferation. Antitumor effects were assessed via cell cycle, apoptosis, and migration and invasion analysis. Cells treated with PF-03084014 were characterized with a gene array analysis combined with Ingenuity Pathway Analysis. The results showed that Notch pathway components were expressed at different levels in DTs. Hes1 (Hes Family BHLH Transcription Factor 1) was overexpressed in DT tumors versus dermal scar tissue, and PF-03084014 caused significant decreases in Notch intracellular domain and Hes1 expression in DT cell strains. PF-03084014 decreased DT cell migration and invasion and also caused cell growth inhibition in DT cell strains, most likely through cell cycle arrest. Gene array analysis combined with Ingenuity Pathway Analysis showed that Wnt1-inducible signaling pathway protein 2 possibly regulated Notch and WNT pathways after treatment with PF-03084014 through integrin. Our findings suggest that the Notch pathway is an important DT therapeutic target. Furthermore, PF-03084014 has significant antitumor activity against DTs, and it may be an alternative strategy for DT treatment. Citation Format: Danielle Braggio, Hui Shang, Ya-Jung Lee, Ghadah A. Al-Sannaa, Chad J. Creighton, Svetlana Bolshakov, Alexander JF Lazar, Dina Lev, Raphael E. Pollock. Targeting the notch pathway: A potential therapeutic approach for desmoid tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2286.

An active bow absorber for vibration reduction of hull girders is presented. In this investigation, the chain locker of ships is designed as the tuned mass of the absorber, which is driven by a hydraulic system. Since the chain locker is very heavy, the absorber will have a high efficiency for vibration reduction. Including the dynamics of the hydraulic system, the control law of the absorber is derived basing on the optimal control and optimum estimation theory. Finally, frequency and time response are considered for a bulk carrier to understand the feasibility of this design. From the simulations, we find the bow absorber is highly effective for vibration reduction of hull girder due to main engine excitation, especially for the lower frequency mode, such as v-2, v-3 and v-4 modes. The required hydraulic force and the displacement of the actuator for reducing the resonance exciting are reasonable. The results also show the effect of vibration suppression by the bow absorber is similar to that by the stern absorber even for the excitation in stern.

The objective of this paper is to analyze the structural dynamic buckling strength of bow structure of a 1,700 TEU container vessel subjected to slamming impact force using finite element method (FEM). The slamming impact load formula suggested by Lloyd’s Register (LR) is used to assess the reliable value of impact force acting on the bow structure. To determine the critical buckling strength of a structure, two methods were developed—a one-time thickness deformation method and a buckling failure method—and are suggested to be used in the future as an industry standard. Various reasons for the causes of structure buckling damage are discussed, including magnitude of impact load, impact duration time and wave impact pattern. The result demonstrates that impact force integration under impact force-time curve is one of the crucial factors for structure dynamic buckling assessment. In the consideration of structure design optimization, this study compares efficient solutions to increase the structure buckling strength. Additionally, this study provides a clear picture of structure dynamic buckling behavior under variant impact force; moreover, it offers the designer solutions to prevent the structure from buckling damage.Copyright © 2012 by ASME

The reduction of hull girder whipping in slamming by an active control system is investigated. Under the consideration of hull flexibility, a mathematical formulation is developed for the whipping of a hull, subject to slamming, and including an active vibration control system consisting of a tuned mass and hydraulic servo system. Using the optimal theory, the control law of the active system is determined. In addition, a closed-loop estimator is introduced to estimate the distribution of hull motion, which is required to compute the actuator output of the active system. Finally, a numerical example of an application to a 205-ton high-speed craft is described. The results show that the whipping will be reduced significantly. The whipping acceleration and induced stress in particular are reduced more than 95% within 2 sec by this scheme.

The impact behavior of composite sandwich panels subjected to a cylindrical impactor is investigated numerically and experimentally. Three kinds of facesheets and two different core densities of sandwich panels are considered in the impact analysis. During the experiment, the impact force and strain history are measured, and the failure is inspected by visual observations. The experimental results show that the impact behavior is mainly controlled by core material. The ABAQUS finite element software is used to analyze the impact responses of sandwich panels. Because of line load conditions, the sandwich panels impacted by the cylindrical impactor is modeled as a 2-D plane strain problem. The numerical results of impact force and strain history are compared with those measured in experiment, it is shown that the experimental results are in good agreement with the finite element solutions. Further, the stresses of sandwich panels are examined. The maximum stress failure criterion is used to estimate the fracture initiation of sandwich panels. Then the experimental and numerical results are compared and discussed.

We describe the synthesis and cellular delivery properties of multivalent and branched delivery systems consisting of cell-penetrating peptides assembled onto a peptide scaffold using Native Chemical Ligation. A trimeric delivery system presenting three copies of the prototypical cell-penetrating peptide TAT shows an endosomolytic activity much higher than its monomeric and dimeric counterparts. This novel reagent promotes the endosomal release of macromolecules internalized into cells by endocytosis and, as a result, it can be used to achieve cytosolic delivery of bioactive but cell-impermeable macromolecules in either cis (covalent conjugation) or trans (simple co-incubation).

HA2-TAT is a peptide-based delivery agent that combines the pH-sensitive HA2 fusion peptide from influenza and the cell-penetrating peptide TAT from HIV. This chimeric peptide is engineered to induce the cellular uptake of macromolecules into endosomes via the TAT moiety and to respond to the acidifying lumen of endosomes to cause membrane leakage and release of macromolecules into cells via the HA2 moiety. The question of how HA2 and TAT affect the properties of one another remains, however, unanswered, and the behavior of the peptide inside endosomes is mostly uncharacterized. To address these issues, the binding and membrane leakage activity of a glutamic acid-enriched analogue E5-TAT was assessed with red blood cells and giant unilamellar vesicles as membrane models for endosomes. Hemolysis and microscopy assays reveal that E5-TAT binds to membranes in a pH-dependent manner and causes membrane leakage by inducing the formation of pores through which macromolecules can escape. The TAT moiety contributes to this activity by causing a shift in the pH response of E5 and by binding to negatively charged phospholipids. On the other hand, TAT binding to glycosaminoglycans reduces the lytic activity of E5-TAT. Addition of TAT to the C-terminus of E5 can therefore either increase or inhibit the activity of E5 depending on the cellular components present at the membrane. Taken together, these results suggest a model for the endosomolytic activity of the peptide and provide the basis for the molecular design of future delivery agents.

This paper is to investigate the failure process and pin-bearing strength of laminated composites under different temperatures. An incremental finite element code, based on the updated Lagrangian approach, was developed for determining the strains dis tribution of laminates under the consideration of the temperature dependent material prop erties. The quadratic failure criterion is adopted for failure predictions. Numerical results include the failure process, failure mode and ultimate bearing strength for two differ ent laminates, S-500 glass/polyester and graphite/epoxy, with three different lay-ups, [0°/45°/90°/-45°]s, [0° 2/ ±45°]s and [90°2/ ±45°]s, as well as with different end distances (e = d-4 d) and widths (W = 1.5 d-6 d). In order to verify the accuracy of the numerical calculations, the bearing strength model test is also made for understanding the effect of temperature on the failure behavior of the laminated composites with pin-loaded hole.

Contact stresses and residual bearing strength of pin-loaded composite laminates at different temperatures are investigated. An incremental finite element code, based on the updated Lagrangian approach, was developed for determining the contact stresses near a pin-loaded hole in composite laminates under combined thermal and mechanical loadings. Based on the progressive damage model, the quadratic strength theory combined with a proposed failure simulation are adopted for failure predictions. In the stress and strength analyses, mechanical properties of the laminates are assumed to be temperature dependent. Numerical results include the distributions of initial (thermal) as well as total contact stress around the pin-loaded hole, residual bearing strength, and failure mode for a single-fastener clearance-fit joint with an elastic pin. The bearing strain model test has been performed at elevated temperature for the verification of present calculations.

Since the response of a panel to moving impact pressure has been shown to differ widely from that to stationary uniform impact pressure. Therefore, before we can clarify the dynamic effect of slamming pressure upon the bottom plate of a high speed craft, a more thoughtful investigation into slamming pressure must be performed, not only the peak values but also the spatial distribution and temporal variation of the water pressure on bottom while travelling in waves.In this paper, a series of test in waves was carried out to measure heave and pitch, acceleration at C. G. and bow, and water pressure at 17 points located on the bottom of a hard chine type model. The time histories of water pressure recorded were compared to the results of the theoretical simulation, which is principally based on a nonlinear strip synthesis. Although the agreement of peak values of impact pressure is less satisfactory, the present theory was confirmed to be a useful method to obtain an overall description of the spatial distribution and temporal variation of the water pressure acting on the bottom of a high speed craft in head sea.

The strength of glass fiber woven roving composites containing a circular hole was examined. Two types of circular hole — drilled, and moulded-in — were considered. Experiments were conducted on four different sizes of hole diameter. Experimental results show that specimens with a moulded-in circular hole exhibit failure at a higher strength than those with a drilled hole and exhibit different failure mode. A strength enhancement of 28–77% as compared with drilled laminates was observed. In addition to explaining the experimental results, a simple finite element model which used the concept of the stream line to simulate the fiber configuration was used in the stress analysis of laminates with moulded-in circular holes. The numerical results may explain why the laminates with moulded-in holes are stronger than those with drilled holes.

Ornithine racemase has been purified to homogeneity from Clostridium sticklandii , as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This is the first racemase known to be highly specific to ornithine. This PLP-dependent enzyme has an M r of 92,000, with a K m for l -ornithine of 0.77 ± 0.05 mM and a k cat of 980 ± 20 s −1 .

A combined numerical and experimental study is conducted to investigate the failure behaviour of bolted connections in vessel made of GFRP laminates. An incremental 3D FEM code, based on the progressive damage model, is developed for determining the stress distributions, damage propagation and ultimate bolted joint strengths of the FRP laminates with different stacking sequences and degrees of lateral clamping. Next, the bearing strength model test is performed to investigate the failure behaviour of the S-500 glass/polyester laminate specimens. The results show that the stacking sequence significantly affects the interlaminar stress concentration on the hole boundary as well as the failure behaviour of pin joint in GFRP laminate. Furthermore, the introduction of a suitable lateral clamping generally improves the normal interlaminar stress state at a bolted joint and also increases the initial delamination strength as well as the ultimate strength of bolted connections in GFRP laminates.