A Comparative Study on the Post-Buckling Behavior of Reinforced Thermoplastic Pipes(RTPs)Under External Pressure Considering Progressive Failure

The collapse pressure is a key parameter when RTPs are applied in harsh deep-water environments.To investigate the collapse of RTPs,numerical simulations and hydrostatic pressure tests are conducted.For the numerical simulations,the eigenvalue analysis and Riks analysis are combined,in which the Hashin failure criterion and fracture energy stiffness degradation model are used to simulate the progressive failure of composites,and the“infinite”boundary conditions are applied to eliminate the boundary effects.As for the hydrostatic pressure tests,RTP specimens were placed in a hydrostatic chamber after filled with water.It has been observed that the cross-section of the middle part collapses when it reaches the maximum pressure.The collapse pressure obtained from the numerical simulations agrees well with that in the experiment.Meanwhile,the applicability of NASA SP-8007 formula on the collapse pressure prediction was also discussed.It has a relatively greater difference because of the ignorance of the progressive failure of composites.For the parametric study,it is found that RTPs have much higher first-ply-failure pressure when the winding angles are between 50°and 70°.Besides,the effect of debonding and initial ovality,and the contribution of the liner and coating are also discussed.

Full-scale pullout tests of rock anchors in a limestone quarry focusing on bond failure at the anchor-grout and grout-rock interfaces

Rock anchors are a common safety measure for stabilising large-scale infrastructure,such as bridge towers,retaining walls,rock slopes and windmills.There are four principal failure modes for rock anchors:(a)tensile failure of the steel anchor,(b)anchor-grout interface failure,(c)grout-rock interface failure,and(d)rock mass uplift.Field tests were performed in a limestone quarry.These tests were designed to test failure modes B and C through pullout.In the tests of failure mode B,the shear stress on the anchor-grout interface is the largest at the top of the grout column and attenuates towards the distal end for small loads.The shear stress becomes uniformly distributed when the applied load is approximately 50%of the ultimate pullout load.The anchors designed to test failure mode C were installed with an endplate and had a higher toughness than the straight bar anchors.The shear stress on the grout-rock interface is the largest at the endplate and attenuates upward before slip starts along the interface.When the ultimate pullout load is reached,and the grout column starts to slip,the shear stress is approximately constant.The bond shear strength on the anchor-grout interface was approximately 20%of the uniaxial compressive strength of the grout,and the bond strength of the grout-rock interface was around 5%for that of the grout.The grout-rock interface is likely determined by whichever is weaker,the grout or the rock.

Norwegian oil and gas storage in rock caverns-Technology based on experience from hydropower development

Underground storage in rock caverns is widely used in Norway for many different petroleum products,such as crude oil,fuel,propane and butane.Basically,the caverns for such storages are unlined,i.e.containment is ensured without using any steel lining or membrane.The main basis for the storage technology originates from the extensive hydropower development in Norway.As part of this activity,about 4500 km of tunnels and shafts have been excavated,and around 200 large powerhouse caverns have been constructed.The hydropower tunnels are mainly unlined,with hydrostatic water pressure on unlined rock of up to 1000 m.Some of the projects also include air cushion chambers with volumes of up to 1×10^(5)m^(3)and air pressure up to 7.7 MPa.Many lessons which are valuable also for underground oil and gas storage have been learnt from these projects.For a storage project to become successful,systematic,well planned design and ground investigation procedures are crucial.The main steps of the design procedure are first to define the optimum location of the project,and then to optimize orientation,shape/geometry and dimensions of caverns and tunnels.As part of the procedure,ground investigations have to be carried out at several steps integrated with the progress of design.The investigation and design procedures,and the great significance of these for the project to become successful will be discussed.Case examples of oil and gas storage in unlined rock caverns are given,illustrating the relevancy of experience from high-pressure hydropower projects for planning and design of unlined caverns for oil and gas storage.

Reliability and Validity of the Norwegian Family Sense of Coherence Scale

Aims and Objectives: To investigate reliability and validity of the translated Norwegian version of the Family Sense of Coherence scale. Background: The Family Sense of Coherence scale measures the global sense of coherence in families and might help health professionals to identify vulnerable families and to facilitate the strengthening of coping strategies in families. Design: Cross-sectional. Methods: In total, 264 parents of children with Attention Deficit Hyperactivity Disorder (ADHD) and 157 parents of children in secondary schools in three municipalities responded to a questionnaire regarding the characteristics of the parent and the child, with four scales: Family Sense of Coherence, Sense of Coherence, Family Assessment Device and Well-being. Statistics with Cronbach alpha, intra-class correlation coefficient, independent sample t-test and Pearson’s correlation coefficient were used to establish the reliability and validity of the scale. Results: Internal consistency with Cronbach’s alpha was acceptable and test-retest reliability with intra-class correlation coefficient was sufficient. Known-groups test revealed statistical differences between the two groups of parents as pre-considered and significant correlations between Family Sense of Coherence and Sense of Coherence, Family Assessment Device and Well-being were found. Conclusion: The Norwegian version of Family Sense of Coherence scale can be considered as reliable and valid for the studied population. Relevance to Clinical Practice: The Family Sense of Coherence scale appears to be an appropriate instrument for evaluating and assessing to find vulnerable families who are in need of interventions strengthening the family’s resources.

Accelerated design of high-performance Mg-Mn-based magnesium alloys based on novel bayesian optimization

Magnesium(Mg),being the lightest structural metal,holds immense potential for widespread applications in various fields.The development of high-performance and cost-effective Mg alloys is crucial to further advancing their commercial utilization.With the rapid advancement of machine learning(ML)technology in recent years,the“data-driven''approach for alloy design has provided new perspectives and opportunities for enhancing the performance of Mg alloys.This paper introduces a novel regression-based Bayesian optimization active learning model(RBOALM)for the development of high-performance Mg-Mn-based wrought alloys.RBOALM employs active learning to automatically explore optimal alloy compositions and process parameters within predefined ranges,facilitating the discovery of superior alloy combinations.This model further integrates pre-established regression models as surrogate functions in Bayesian optimization,significantly enhancing the precision of the design process.Leveraging RBOALM,several new high-performance alloys have been successfully designed and prepared.Notably,after mechanical property testing of the designed alloys,the Mg-2.1Zn-2.0Mn-0.5Sn-0.1Ca alloy demonstrates exceptional mechanical properties,including an ultimate tensile strength of 406 MPa,a yield strength of 287 MPa,and a 23%fracture elongation.Furthermore,the Mg-2.7Mn-0.5Al-0.1Ca alloy exhibits an ultimate tensile strength of 211 MPa,coupled with a remarkable 41%fracture elongation.

Adhesion strength of tetrahydrofuran hydrates is dictated by substrate stiffness

Understanding the hydrate adhesion is important to tackling hydrate accretion in petro-pipelines.Herein,the relationship between the Tetrahydrofuran(THF)hydrate adhesion strength(AS)and surface stiffness on elastic coatings is systemically examined by experimental shear force measurements and theoretical methods.The mechanical factor-elastic modulus of the coatings greatly dictates the hydrate AS,which is explained by the adhesion mechanics theory,beyond the usual factors such as wettability and structural roughness.Moreover,the hydrate AS increases with reducing the thickness of the elastic coatings,resulted from the decrease of the apparent surface elastic modulus.The effect of critical thickness for the elastic materials with variable elastic modulus on the hydrate AS is also revealed.This study provides deep perspectives on the regulation of the hydrate AS by the elastic modulus of elastic materials,which is of significance to design anti-hydrate surfaces for mitigation of hydrate accretion in petro-pipelines.

Principles and methods of rock support for rockburst control

This paper presents the principles of rock support for rockburst control and three rockburst support systems used in deep metal mines.Before the principles of rock support are presented,rock fracture related to strain burst is first discussed with the help of photos taken on site,and the energy sources and transformations during bursting are illustrated through conceptual models.Surface parallel extension fracture usually occurs in the ejected and surrounding rocks in a strain burst event,while the ejected rock in a fault-slip rockburst is often already pre-fractured before the event.There must be excessive release energy available for rock ejection.The excessive release energy comes from both the ejected rock itself and the surrounding rock.To prevent rock ejection in a rockburst,the support system must be able to dissipate the excessive release energy.All support devices in a support system for rockburst control must be able to dissipate energy,be firmly linked,and be compatible in deformability.A support system for rockburst control comprises surface-retaining devices and yield rockbolts as well as yield cablebolts when needed.Laying mesh on the top of shotcrete liner is a good practice to enhance the surfaceretaining capacity of the support system.Energy-absorbing yield rockbolts dissipate energy either by stretching of the bolt shank or by sliding of the inner anchor in the borehole.Mesh,mesh strap and shotcrete are the surface-retaining devices widely used in the current rock support systems.The three types of rock support used for rockburst control at present are soft support system using Split Set bolts,hybrid support system using rebar and two-point anchored yield bolts,and entirely yieldable support system using strong yield bolts.

Core-shell particles of C-doped CdS and graphene: A noble metal-free approach for efficient photocatalytic H_(2) generation

To achieve efficient photocatalytic H_(2) generation from water using earth-abundant and cost-effective materials,a simple synthesis method for carbon-doped CdS particles wrapped with graphene(C-doped CdS@G)is reported.The doping effect and the application of graphene as cocatalyst for CdS is studied for photocatalytic H_(2) generation.The most active sample consists of CdS and graphene(CdS-0.15G)exhibits promising photocatalytic activity,producing 3.12 mmol g^-(1) h^-(1) of H_(2) under simulated solar light which is^4.6 times superior than pure CdS nanoparticles giving an apparent quantum efficiency(AQY)of 11.7%.The enhanced photocatalytic activity for H_(2) generation is associated to the narrowing of the bandgap,enhanced light absorption,fast interfacial charge transfer,and higher carrier density(N_(D))in C-doped CdS@G samples.This is achieved by C doping in CdS nanoparticles and the formation of a graphene shell over the C-doped CdS nanoparticles.After stability test,the spent catalysts sample was also characterized to investigate the nanostructure.

Integrate ecosystem services into socio-economic development to enhance achievement of sustainable development goals in the post-pandemic era

The COVID-19 pandemic has stalled and rolled back progress on Sustainable Development Goals(SDGs).Ecosys-tem services(ESs),defined as the contributions of ecosystems to human well-being,underpin the achievement of SDGs.To promote SDG achievement in post-pandemic era,we teased out the links between ESs and SDGs while examining the impact of COVID-19.We found that ESs benefited all SDGs,yet man-made pressures led to degra-dation of ecosystems and their services.There is broad consensus that the virus lurks in degraded ecosystems and generates spillover due to human interference.The pandemic and global lockdown/restriction disrupted the flow of ESs and altered human ESs demand,threatening the efforts for the SDGs.We suggested:1)to study the association and traceability of ESs-SDGs under the pandemic;2)to prioritize pressing issues such as health care,livelihood,and resource security and in the long run,we should promote human-nature harmony to achieve the SDGs;and 3)to enhance ESs and to promote the SDGs through local community efforts,ESs accounting,and ecosystem restoration.This paper provides insights into the importance of ESs to the SDGs and the ways to integrate ESs into socio-economic development to promote the SDG achievement after the pandemic.

A review on the performance of conventional and energy-absorbing rockbolts

This is a review paper on the performances of both conventional and energy-absorbing rockbolts manifested in laboratory tests. Characteristic parameters such as ultimate load, displacement and energy absorption are reported, in addition to load-displacement graphs for every type of rockbolt. Conventional rockbolts refer to mechanical rockbolts, fully-grouted rebars and frictional rockbolts. According to the test results, under static pull loading a mechanical rockbolt usually fails at the plate; a fully-grouted rebar bolt fails in the bolt shank at an ultimate load equal to the strength of the steel after a small amount of displacement; and a frictional rockbolt is subjected to large displacement at a low yield load. Under shear loading, all types of bolts fail in the shank. Energy-absorbing rockbolts are developed aiming to combat instability problems in burst-prone and squeezing rock conditions. They absorb deformation energy either through ploughing/slippage at predefined load levels or through stretching of the steel bolt. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of the energy-absorbing bolts is much larger than that of all conventional bolts. The dynamic load capacity is smaller than the static load capacity for the energy-absorbing bolts displacing based on ploughing/slippage while they are approximately the same for the D-Bolt that displaces based on steel stretching.

Modelling of a tubular membrane contactor for pre-combustion CO_2 capture using ionic liquids:Influence of the membrane configuration, absorbent properties and operation parameters

A membrane contactor using ionic liquids(ILs) as solvent for pre-combustion capture CO_2 at elevated temperature(303-393 K) and pressure(20 bar) has been studied using mathematic model in the present work. A comprehensive two-dimensional(2 D) mass-transfer model was developed based on finite element method. The effects of liquid properties, membrane configurations, as well as operation parameters on the CO_2 removal efficiency were systematically studied. The simulation results show that CO_2 can be effectively removed in this process. In addition, it is found that the liquid phase mass transfer dominated the overall mass transfer. Membranes with high porosity and small thickness could apparently reduce the membrane resistance and thus increase the separation efficiency. On the other hand, the membrane diameter and membrane length have a relatively small influence on separation performance within the operation range.

Testing and modeling of cyclically loaded rock anchors

The Norwegian Public Roads Administration(NPRA) is planning for an upgrade of the E39 highway route at the westcoast of Norway. Fixed links shall replace ferries at seven fjord crossings. Wide spans and large depths at the crossings combined with challenging subsea topography and environmental loads call for an extension of existing practice. A variety of bridge concepts are evaluated in the feasibility study. The structures will experience significant loads from deadweight, traffic and environment. Anchoring of these forces is thus one of the challenges met in the project. Large-size subsea rock anchors are considered a viable alternative. These can be used for anchoring of floating structures but also with the purpose of increasing capacity of fixed structures. This paper presents first a thorough study of factors affecting rock anchor bond capacity. Laboratory testing of rock anchors subjected to cyclic loading is thereafter presented. Finally, the paper presents a model predicting the capacity of a rock anchor segment, in terms of a ribbed bar, subjected to a cyclic load history. The research assumes a failure mode occurring in the interface between the rock anchor and the surrounding grout. The constitutive behavior of the bonding interface is investigated for anchors subjected to cyclic one-way tensile loads. The model utilizes the static bond capacity curve as a basis, defining the ultimate bond sbuand the slip s1 at τ. A limited number of input parameters are required to apply the model. The model defines the bond-slip behavior with the belonging rock anchor capacity depending on the cyclic load level(τcy/τ), the cyclic load ratio(R= τcy/τcy), and the number of load cycles(N). The constitutive model is intended to model short anchor lengths representing an incremental length of a complete rock anchor.

Experimental study and stress analysis of rock bolt anchorage performance

A new method was developed to apply pull-and-shear loads to the bolt specimen in order to evaluate theanchorage performance of the rebar bolt and the D-Bolt. In the tests, five displacing angles （0°, 20°, 40°,60°, and 90°）, two joint gaps （0 mm and 30 mm）, and three kinds of host rock materials （weak concrete,strong concrete, and concrete-granite） were considered, and stressestrain measurements were conducted.Results show that the ultimate loads of both the D-Bolt and the rebar bolt remained constantwith any displacing angles. The ultimate displacement of the D-Bolt changed from 140 mm at the0 displacing angle （pure pull） to approximately 70 mm at a displacing angle greater than 40. Thedisplacement capacity of the D-Bolt is approximately 3.5 times that of the rebar bolt under pure pull and50% higher than that of the rebar bolt under pure shear. The compressive stress exists at 50 mm from thebolt head, and the maximum bending moment value rises with the increasing displacing angle. The rebarbolt mobilises greater applied load than the D-Bolt when subjected to the maximum bending. Theyielding length （at 0） of the D-Bolt is longer than that of the rebar bolt. The displacement capacity of thebolts increased with the joint gap. The bolt subjected to joint gap effect yields more quickly with greaterbending moment and smaller applied load. The displacement capacities of the D-Bolt and the rebar boltare greater in the weak host rock than that in the hard host rock. In pure shear condition, the ultimateload of the bolts slightly decreases in the hard rock. The yielding speed in the hard rock is higher thanthat in the weak rock. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.

Coupling of discrete-element method and smoothed particle hydrodynamics for liquid-solid flows

Particle based methods can be used for both the simulations of solid and fluid phases in multiphase medium, such as the discrete-element method for solid phase and the smoothed particle hydrodynamics for fluid phase. This paper presents a computational method combining these two methods for solid-liquid medium. The two phases are coupled by using an improved model from a reported Lagrangian-Eulerian method. The technique is verified by simulating liquid-solid flows in a two-dimensional lid-driven cavity.

Physical Properties in Drying of Food Products with Combined Sublimation and Evaporation

Drying is an important unit operation in processing of biological resources. The drying process may influence the product properties and quality, which may shrink, break or undergo rheological, physical and biochemical changes. The important parameters responsible for such changes are drying conditions, type of drying technology and residence drying time. Thermal conductivity, thermal-mass diffusivity, enthalpy, porosity and density are the main material property and heat-mass transfer parameters, which are essential for understanding the changes in product quality and for designing and dimensioning the drying processes. In this paper physical properties of food products undergoing a combined sublimation and evaporation were studied. Pieces of vegetables and potatoes were dried in a heat pump fluidized bed dryer at combined modes with temperatures below the freezing point in the beginning and a final drying step at temperatures above the freezing point. Samples of products were tested at different moisture contents with respect to physical properties. Physical properties of leek and potato samples were measured and mass diffusivities were determined from drying kinetic data. Based on bulk density and rehydration measurements it was clearly observed that drying temperature and modes influenced the final product physical properties. The potato cube run dried with initial atmospheric freeze-drying step had rehydration ability 430%above a run dried only above the freezing point. The average effective mass diffusivity for 5 mm slabs of leek was 0.5 x 10-11m2·s-1 for the sublimation stage and 2.2 x 10-11m2·s-1 for the evaporation stage.

Comprehensive Insight into the Mechanism, Material Selection and Performance Evaluation of Supercapatteries

Electrochemical energy storage devices(EESs)play a crucial role for the construction of sustainable energy storage system from the point of generation to the end user due to the intermittent nature of renewable sources.Additionally,to meet the demand for next-generation electronic applications,optimizing the energy and power densities of EESs with long cycle life is the crucial factor.Great e orts have been devoted towards the search for new materials,to augment the overall performance of the EESs.Although there are a lot of ongoing researches in this field,the performance does not meet up to the level of commercialization.A further understanding of the charge storage mechanism and development of new electrode materials are highly required.The present review explains the overview of recent progress in supercapattery devices with reference to their various aspects.The di erent charge storage mechanisms and the multiple factors involved in the performance of the supercapattery are described in detail.Moreover,recent advancements in this supercapattery research and its electrochemical performances are reviewed.Finally,the challenges and possible future developments in this field are summarized.

Development and behavior of Plaintive Cuckoo(Cacomantis merulinus) nestlings and their Common Tailorbird(Orthotomus sutorius) hosts

Background:Our knowledge of avian brood parasitism is primarily based on studies of a few selected species.Recently,researchers have targeted a wider range of host–parasite systems,which has allowed further evaluation of hypotheses derived from well-known study systems but also disclosed adaptations that were previously unknown.Here we present developmental and behavioral data on the previously undescribed Plaintive Cuckoo(Cacomantis merulinus) nestling and one of its hosts,the Common Tailorbird(Orthotomus sutorius).Methods:We discovered more than 80 Common Tailorbird nests within an area of 25 km2,and we recorded nestling characteristics,body mass,tarsus length and begging display every 3 days for both species.Results:Plaintive Cuckoo nestlings followed a developmental pathway that was relatively similar to that of their well-studied relative,the Common Cuckoo(Cuculus canorus).Tailorbird foster siblings were evicted from the nest rim.The cuckoo nestlings gained weight faster than host nestlings,and required 3–9 days longer time to fledge than host nestlings.Predation was high during the early stages of development,but the nestlings acquired a warning display around 11 days in the nest,after which none of the studied cuckoo nestlings were depredated.The cuckoos' begging display,which appeared more intense than that of host nestlings,was initially vocally similar with that of the host nestlings but began to diverge from the host sound output after day 9.Conclusions:The developmental data on Plaintive Cuckoo nestlings and their tailorbird host builds an important foundation for future work on the co-evolutionary interactions in this parasite–host system.

Effect of neat and reinforced polyacrylonitrile nanofibers incorporation on interlaminar fracture toughness of carbon/epoxy composite

This paper presents an experimental investigation on fracture behavior of epoxy resin-carbon fibers composites interleaved with both neat polyacrylonitrile （PAN） nanofibers and A1203-PAN nanofibers. In particular, the paper focuses on the effect of adding Al2O3 nanopartiles in PAN nanofibers, which were incorporated in unidirectional （UD） laminates. The effectiveness of adding a thin film made of Al2O3-PAN on the fracture behavior of the carbon fiber reinforced polymer （CFRP） has been addressed by comparing the energy release rates, obtained by testing double cantilever beam （DCB） samples under mode I loading condition. A general improvement in interlaminar fracture energy of the CFRP is observed when the both neat PAN nanofibers and Al2O3-PAN nanofibers are interleaved. However, higher interlaminar strength has been observed for the samples with a thin film of Al2O3-PAN nanofibers, suggesting a better stress distribution and stress transformation from resin-rich area to reinforcement phase of hybrid composites.

Prognostic Significance of EGFR Gene Amplification and Overexpression in Diffuse Astrocytomas—A Literature Study

Epidermal growth factor receptor (EGFR) has been shown to play an important role in the malignant progression of diffuse astrocytomas. Numerous studies have investigated the clinical significance of overexpression and amplification of the EGFR gene in these tumours with ambiguous results. The aim of this study was therefore to review the literature to get the current prognostic and diagnostic status. The PubMed database was used to search for papers in English in the time period 1987-2010 using the following keywords: astrocytoma, glioma, c-erbB1, EGFR, glioblastoma, HER1 and prognosis. Other inclusion criteria were: 1) studies with more than 50 patients;2) patient age over 18 years;3) tumour grading according to the latest World Health Organization (WHO) classification (2007) and 4) EGFR overexpression assessed by immunohistochemistry. A total of 47 publications were included and several reported positive correlations between both EGFR gene amplification and overexpression with histological malignancy grade and survival. The results are, however, encumbered with elements of uncertainty involving for instance methodological diversities and small number of patients. Larger studies with standardized procedures are necessary to fully clarify the clinical role of EGFR in human astrocytomas.

A Semi-Supervised Approach for Aspect Category Detection and Aspect Term Extraction from Opinionated Text

The Internet has become one of the significant sources for sharing information and expressing users’opinions about products and their interests with the associated aspects.It is essential to learn about product reviews;however,to react to such reviews,extracting aspects of the entity to which these reviews belong is equally important.Aspect-based Sentiment Analysis(ABSA)refers to aspects extracted from an opinionated text.The literature proposes different approaches for ABSA;however,most research is focused on supervised approaches,which require labeled datasets with manual sentiment polarity labeling and aspect tagging.This study proposes a semisupervised approach with minimal human supervision to extract aspect terms by detecting the aspect categories.Hence,the study deals with two main sub-tasks in ABSA,named Aspect Category Detection(ACD)and Aspect Term Extraction(ATE).In the first sub-task,aspects categories are extracted using topic modeling and filtered by an oracle further,and it is fed to zero-shot learning as the prompts and the augmented text.The predicted categories are the input to find similar phrases curated with extracting meaningful phrases(e.g.,Nouns,Proper Nouns,NER(Named Entity Recognition)entities)to detect the aspect terms.The study sets a baseline accuracy for two main sub-tasks in ABSA on the Multi-Aspect Multi-Sentiment(MAMS)dataset along with SemEval-2014 Task 4 subtask 1 to show that the proposed approach helps detect aspect terms via aspect categories.