Envelope Surface Research Articles

CoolSkin

The article investigates the dependencies of façade design and construction in the integration of a sustainable solar-powered cooling system based on closed adsorption. The presented work focuses on the possible design variants of the envelope surface of the façade -integrated adsorber. The principle of adsorption cooling is presented and, based on this, architectural options for façade integration are investigated. This is done both constructively and visually. For each variant, the solar gains are summed up and compared with each other. A functionally designed adsorber, similar to a flat plate collector, serves as a reference and starting point for the modifications. It provides the comparative value for the energy evaluation. The modification is limited to the visible surface of the absorber. The texture of the solar adsorbing sheet was changed and the glazing used was replaced by ETFE cushions and by a novel ETFE vacuum panel. Finally, the solar simulation results were integrated into the higher-level system simulation to evaluate the resulting gain in cooling capacity. The results show that the system could generate more than 100 W per installed square metre of adsorber façade. Furthermore, higher solar gains compared to the reference case can be obtained at particular times of the day due to geometry and material changes. However, the modifications always lead to a reduction of the total cooling power. In conclusion, the simulation results reveal that design flexibility is possible, but currently the studied design variants have a lower cooling capacity compared to the solely functionally designed adsorber.

Wind-driven rainwater penetration through brick veneer with and without surface treatments

Rainwater penetration through building enclosures is a critical factor affecting building performance and durability. Understanding and assessing rainwater penetration and its prevention through the brick veneer and brick wall is crucial to controlling and avoiding moisture-related problems such as fungal growth and damages in interior structural elements. Addition of a layer of clay bricks as a cladding (veneer) to the exposed surface of a building envelope is a common practice in Canada. Though clay brick veneer provides adequate weather resistance for the building, it does not offer complete resistance to wind-driven rainwater penetration unless other measures such as surface treatment or additional layer of cladding is incorporated. Hence, studying the aspects of resistance to water penetration of commonly used cladding systems is of utmost importance. This paper presents outcomes of an experimental study conducted to determine water penetration of brick veneer specimens with two different initial rate of absorption values, two void amounts, and three different surface treatments. The study found that the surface treatment is a viable method for improving the resistance of water penetration inside the building envelope and the plastering was found to be the most effective method. The study also found that the initial rate of absorption and thickness of the bricks affect the water penetration; however, void amount in the brick does not affect much on water leakage of the masonry walls. • This paper presents various options to minimize and stop water penetration into the building envelope. • Three different surface treatments of brick veneer on rainwater penetration were studied. • Surface treatment with plaster is able to completely prevent water penetration. • Between the two water repellent treatments, water-based water repellent showed a better performance. • The paper also presents effect of IRA and void percentage of clay bricks on rainwater penetration.

Tackling the Future Pandemics: Broad-Spectrum Antiviral Agents (BSAAs) Based on A-Type Proanthocyanidins.

A-type proanthocyanidins (PAC-As) are plant-derived natural polyphenols that occur as oligomers or polymers of flavan-3-ol monomers, such as (+)-catechin and (-)-epicatechin, connected through an unusual double A linkage. PAC-As are present in leaves, seeds, flowers, bark, and fruits of many plants, and are thought to exert protective natural roles against microbial pathogens, insects, and herbivores. Consequently, when tested in isolation, PAC-As have shown several biological effects, through antioxidant, antibacterial, immunomodulatory, and antiviral activities. PAC-As have been observed in fact to inhibit replication of many different human viruses, and both enveloped and non-enveloped DNA and RNA viruses proved sensible to their inhibitory effect. Mechanistic studies revealed that PAC-As cause reduction of infectivity of viral particles they come in contact with, as a result of their propensity to interact with virion surface capsid proteins or envelope glycoproteins essential for viral attachment and entry. As viral infections and new virus outbreaks are a major public health concern, development of effective Broad-Spectrum Antiviral Agents (BSAAs) that can be rapidly deployable even against future emerging viruses is an urgent priority. This review summarizes the antiviral activities and mechanism of action of PAC-As, and their potential to be deployed as BSAAs against present and future viral infections.

Air Cavity Building Walls: A Discussion on the Opportunity of Filling Insulation to Support Energy Performance Improvement Strategies

The paper intends to discuss the use of cavity wall insulation in existing buildings for energy improvement. Cavity walls are widely spread throughout the EU, typically in buildings from the 20th century, which are recognized as the subject of urgent and deep energy renovation interventions. Their main characteristic is an empty air cavity between two layers of building materials (typically brick, stone, or concrete). Filling the empty air cavity with insulating materials reduces energy loss by transmission through opaque envelope surfaces, and therefore, it represents a cheap solution to obtain a significant reduction in building energy consumption. Various aspects should be carefully evaluated for the effectiveness of this type of intervention: The first step is knowing the materials’ behavior depending on their thermal and hygrometric parameters (conductivity and transmittance, thermal bridge transmittance, vapor permeability, and resistance to vapor diffusion). Some indications on limits or reference/target values are usually given by national/regional laws and EU Directives. The filling insulation could lead to collateral problems (thermal bridges, risk of vapor condensation inside walls, etc.). To help understand the relevance and the impact of this insulation technique, an example of the assessments of a common cavity wall type is presented. The analyses highlight the usefulness of an organized and systematic database on building envelope features to set targeted energy-saving actions. Public administrations could base their strategies on this information to promote the reduction of energy consumption on a large scale with efficient and economically sustainable interventions. In the absence of more specific databases, the Energy Performance Certificates (EPC) data consulting could help develop thermal insulation strategies at a regional/national level. In particular, the diffusion of cavity walls can be obtained as a function of wall surface and cavity thickness for estimating the energy saving potential, economic impact, and general feasibility of systematic insulation-filling actions. An example of this kind of database analysis is discussed and carried out on a regional scale to explain how it could represent a useful approach to evaluate potential energy-saving interventions. The sample building stock provides suggestions on the possibility to extend the considerations on a larger scale to help set systematic energy-saving strategies.

Experiment on Space-Time Evolution Characteristics of Deformation and Failure of Overlying strata in Longwall Mining of Steeply Dipping Coal Seam

Revealing the space-time evolution characteristics of overlying strata deformation and failure is the key for safe and efficient mining of steeply dipping coal seam. In this paper, based on the physical similarity simulation experiment and field measurement method, the non-uniform filling characteristics of gangue in gob and the roof migration law are comprehensively determined, the evolution characteristics and distribution patterns of the abutment pressure in the upper and lower sections, the distribution characteristics of the working resistance of the support, and the regional strata behavior law in the mining process are analyzed, and the technical measures for the stability control of the support in steeply dipping coal seam are put forward. Results shown: With the advancing distance increases, the accumulation range of gangue increases, and the inverted triangle airspace begins to appear repeatedly in the gob behind the support. In the deep gob, the angle between the gangue pile and the horizontal plane decreases continuously from the lower part to the upper part along the inclined direction. Horizontal displacement, vertical displacement and combined displacement of roof show an evolutionary trend of ‘increase – stability’. The peak displacement position moves from the upper part to the middle part of the working face, which is located at the hinge point between the broken block and the failure envelope surface. The evolution of abutment pressure of headgate and tailgate T-junction shows a trend of ‘increase – stability’. The peak and concentration coefficient at headgate T-junction are greater than tailgate T-junction. The load imbalance characteristics of the support in working face are obvious, and the basic characteristics along the inclined direction are the largest in the middle area, the second in the upper and the smallest in the lower area. The initial force and working resistance of support should be improved, and the position of the support should be adjusted in time in practical engineering. The results provide reference and guidance for practical production.

Hydrodynamical simulations for the common-envelope wind model for Type Ia supernovae

Context. The single-degenerate (SD) model is one of the leading models for the progenitors of Type Ia supernovae (SNe Ia). Recently, a new version of the SD model, the common-envelope wind (CEW) model, has been proposed, which, in principle, has the potential to resolve most of the difficulties encountered by previous SD models. This model is still being developed and a number of open issues remain, such as the details of the mass-loss mechanism from the surface of the common envelope (CE), the main observational properties, and the spiral-in timescale of the binary inside the envelope. Aims. In this article, we aim to address these issues by considering hydrodynamical effects on the CE. Methods. Using the stellar evolution code MESA, we carried out a series of 1D hydrodynamical simulations of an asymptotic giant branch (AGB) star undergoing a common-envelope phase with different envelope masses (0.0007 M⊙–0.06 M⊙). The effect of the immersed binary was mimicked by changing the gravitational constant throughout the envelope and injecting an extra heating source at the location of the binary orbit. Results. We found that the envelopes are always dynamically unstable, leading to regular mass ejection events if the envelope is more massive than the critical value of ∼0.003 M⊙. The κ mechanism can naturally explain this phenomenon. We also found that, due to the low mass of the CE, the estimated frictional luminosity caused by the spiral-in of the immersed binary is much less than the nuclear luminosity, and therefore will not affect the structure of the CE significantly. Conclusions. Our results imply that the CE in the CEW model cannot be very massive. We also present a rough estimate for the spiral-in timescale based on a simplified model. We found that, for reasonable assumptions, the timescale may be longer than a few 105 yr; therefore, the white dwarf (WD) may have enough time to increase its mass toward the Chandrasekhar mass, avoiding a merger with the companion.

CWE identification and cutting force prediction in ball-end milling process

Ball-end milling of sculptured surfaces is an efficient and cost effective manufacturing technique when compared with other methods. However, an accurate cutting force prediction is still challenging when the Cutter Workpiece Engagement (CWE) and Instantaneous Undeformed Chip Thickness (IUCT) vary simultaneously. In order to predict the milling force accurately, an algorithm is designed to obtain the CWE boundaries with the variable tool orientations. Inspired by the main idea of analytical CWE model, an improved Z-map method is developed, which is based on the classic Z-map method. The point cloud of tool envelope surface method is generated based on the classic Z-map and the points of the CWE are screened according to the chosen criteria. Afterwards, the IUCT is calculated numerically by the accurate cutting thickness model. In order to overcome the drawbacks of the IUCT method, a simplified IUCT model is proposed to eliminate the iterative calculation. Related milling experiments were carried out on Al7075 workpiece to validate the proposed models showing a good agreement with errors smaller than 12.5%. It can be concluded from simulation results that tool postures have a significant effect on the machining process. This contributes to in-depth understanding the material removal process and optimizing the process parameters of multi-axis machining processes.

Preliminary measurement and analysis of the condylar movement envelope surface parameters in healthy adults

Objective: To measure and analyze parameters of the three-dimensional (3D) model of the condylar movement envelope surface (ES) and provide a reference for the design of the temporomandibular prosthesis. Methods: Thirty-four healthy adults aged (25.4±2.8) years were recruited from the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology as subjects. There were 9 males and 25 females, most of them were university students and others outside the university have received undergraduate education or above. Condylar movement ES were obtained using the previous method on the 3D trajectory of condyle. The simulations of condylar movement were projected according to opening movements, protrusion movements, and lateral movements respectively. The total area of the ES and the area proportions of models formed by above different mandibular movements were measured and calculated. The adults' head and maxillofacial 3D models reconstructed by cone beam CT were registered with ES in Geomagic Studio. The inner and outer poles of the condyle, the corrective sagittal axis of the ES, and the median sagittal plane (MSP) were calibrated in registration models using Geomagic Studio, and the parameters were measured as follows: the anteroposterior and medialateral diameters of the condyle, the anteroposterior diameters and the transverse diameters (anterior, middle and posterior parts) of the ES, the angles between the corrective sagittal axis of the ES and MSP (ES-MSP). Pearson correlation analysis was performed by SPSS 24.0. Results: The total area of the ES was (760±133) mm2, the opening movement part accounted for (63.3±15.2)%, the protrusion movement part accounted for (14.9±9.6)%, the lateral movement part accounted for (21.8±13.3)%. Parameter measurements were as follows: mediolateral diameters of condyle was (19.8±2.3) mm; anteroposterior diameter of the ES was (21.2±3.1) mm, the transverse diameters (anterior, middle and posterior parts) of the ES were (20.6±2.4), (20.4±2.4), (22.0±2.6) mm, respectively; the transverse diameters of the ES were about 2 mm larger than that of the condyle. The angle between the corrective sagittal axis of ES and the MSP was 6.8°±6.2°. The coefficient of variation (CV) in these parameters showed: CV of the transverse diameters (anterior, middle and posterior parts) of the ES and mediolateral diameter of the condyle were 0.98, 0.99, 0.93, respectively (P<0.001). CV of aera of ES and mediolateral diameter of the condyle was 0.64 (P=0.002). CV of aera of ES and anteroposterior diameter of ES was 0.62 (P=0.004). Conclusions: The 3D envelope surface model formed by mandibular opening movements accounted for the largest proportion of the ES. The corrective sagittal axis of the ES was at an angle to the MSP, the transverse diameters (anterior, middle and posterior parts) of the ES were approximately 2 mm larger than the mediolateral diameter of the condyle, the transverse diameters (anterior, middle and posterior parts) of the ES were highly positively correlated with the mediolateral diameter of the condyle.

A High-Accuracy Tool Path Generation (HATPG) Method for 5-Axis Flank Milling of Ruled Surfaces with a Conical Cutter Based on Instantaneous Envelope Surface Modelling

In this paper, a novel framework of generating high-accuracy tool path for 5-axis flank milling of ruled surfaces with a conical cutter is developed by designing the instantaneous envelope surface of each planned cutter location (CL). Based on the analysis of the envelope theory, the instantaneous envelope profile of a selected cutter is only affected by the first-order derivation of the cutter’s motion, i.e. tangent vectors of the tool path. This property reveals an interesting fact that characteristic points on an envelope surface can be controlled via path tangents, thus laying the foundation for accurately evaluating the machining error at a single cutter location. On this basis, a simple yet robust method, called rotations for three-point offset (RTPO) method is first proposed to position a conical cutter to have at least three contact points with a ruled surface. Path tangents optimization is then performed to minimize the geometric deviation between the characteristic points and the ruled surface, followed by fine-tuning of the tool axis with a differential rigid motion. Both path tangent optimization and tool axis tuning are formulated as linear program problems, and the optimal cutter location with path tangents is determined by solving them repetitively. Finally, accurate tool path for conical cutter flank milling is generated with curve registration algorithms that interpolate the planned points and tangents. Examples are provided to validate the proposed method, and one can see high-accuracy flank milling paths can be planned point-by-point without subsequent optimization.

Lectins from plants and algae act as anti-viral against HIV, influenza and coronaviruses.

BackgroundCarbohydrate–lectin interactions are extremely specific as the lectin is capable of recognising monomeric and oligomeric sugars in a reversible manner. It has been known for a long time that lectins have antibacterial, antifungal, and insecticidal activities. Recently, it has been reported that many lectins can prevent the virus growth by interacting with the viral envelop surface glycoprotein. Spike protein, which is found on the surface of some enveloped viruses, is heavily mannosylated and will have strong affinity for mannose specific lectins. According to the findings, lectins have a high binding affinity for the glycans of the SARS-CoV-2 spike glycoprotein, which contains N-glycosylation sites. As a result, various lectins are being researched and developed as anti-viral agents.ResultsAccording to our in silico studies, the amino acid residues Asn487, Tyr489, Gln493, Lys417, and Tyr505 of the receptor binding domain (RBD) of SARS-CoV-2 formed an interaction with the model lectin Lablab purpureus lectin. Similar interaction for SARS-CoV-2 spike protein was observed with Griffithsin lectin (algal source) as well. These observations demonstrate that lectins could be one of the potential molecules for neutralising coronavirus infection.ConclusionThis review focuses on anti-viral lectins isolated and characterized from plants and algae (last 5 years) and showed anti-viral properties against HIV, Influenza, and coronaviruses.

Realistic modeling of cemented granular materials with a lattice spring model by developing a digital 3D reconstruction approach

AbstractThree‐dimensional (3D) geometric reconstruction is a fundamental requirement to realistically predict the mechanical behavior of cemented granular materials (CGMs). In this work, a four‐phase geometric reconstruction method for CGMs, involving aggregate, cement, in‐between interfacial transition zone (ITZ), and void phases, is developed by using digital image processing techniques and an optimization algorithm. The reconstruction method includes four steps. (1) The planar outlines of aggregates are extracted from a two‐dimensional (2D) aggregate image (e.g., gravels, pebbles, and crushed stones) based on the image segmentation algorithm. (2) Through spatial geometric transformations on the acquired planar outlines, the 3D aggregates are generated, whose reliability is verified by comparison with those obtained by a 3D scanner. (3) According to the volume ratio of each phase, the initial four‐phase model is reconstructed by randomly placing aggregates into the user‐defined domain with considering the size distribution of aggregates, followed by the generation of the ITZ represented by their surrounding minimum envelope surface, and the insertion of voids in the rest cement phase. (4) The final realistic CGM is reconstructed by optimizing the spatial distribution of the void and cement phases based on a simulated annealing algorithm. Afterwards, the rationality of the reconstructed CGM is verified by comparing two‐point probability functions between the physical model and the reconstructed model. With the aid of a four‐dimensional lattice spring model (4D‐LSM), the feasibility of the reconstructed CGM to reproduce its mechanical behavior is demonstrated by numerical examples and a comparison with existing experimental or other numerical solutions.

A role for an HTLV-1 vaccine?

HTLV-1 is a global infection with 5-20 million infected individuals. Although only a minority of infected individuals develop myelopathy, lymphoproliferative malignancy, or inflammatory disorders, infection is associated with immunosuppression and shorter survival. Transmission of HTLV-1 is through contaminated blood or needles, mother-to-child exposure through breast-feeding, and sexual intercourse. HTLV-1 is a delta retrovirus that expresses immunogenic Gag, Envelope, TAX, and Hbz proteins. Neutralizing antibodies have been identified directed against the surface envelope protein, and cytotoxic T-cell epitopes within TAX have been characterized. Thus far, there have been few investigations of vaccines directed against each of these proteins, with limited responses, thus far. However, with new technologies developed in the last few years, a renewed investigation is warranted in search for a safe and effective HTLV-1 vaccine.

Permeability prediction in geotextile envelope after chemical clogging: a coupled model

This study develops a coupled model of chemical clogging and permeability coefficient of geotextile envelope. Based on the distribution characteristics of crystal precipitates on geotextile envelope and their influence on the permeability coefficient, a permeability coefficient model of an actual geotextile envelope that considers the overlapping effect is developed. Then, the densification effects of geosynthetic fiber hypothesis and the filter cake effect hypothesis are proposed to simulate the processes of increasing fiber diameter after crystal precipitation and the accumulation of crystal precipitates on the surface of geotextile envelope. The crystal precipitation module and permeability coefficient module are coupled, and their experimental values are used to confirm the availability of the model. Results indicate the satisfactory performance of the model. In addition, the parameter sensitivity analysis and trend prediction show that the saturation index SI and solution flow rate V are the main factors that affect the chemical clogging and permeability of geotextile envelope. When the solution conditions are not considered, the sensitivity of geotextile envelope parameter df increased with the amount of precipitation in crystal precipitation. When the pores of the geotextile envelope are completely clogged, the permeability coefficient of the geotextile envelope will drop sharply, then decline slowly.

Hygrothermal performance assessment of a bio-based building made with date palm concrete walls

The current research falls within the general context of expanding and developing bio-based materials as insulating and low-cost construction materials. This paper aims to investigate the effect of mass transfer on hygrothermal conditions, and the energy consumption of a building made with date palm concrete (DPC). As well as, highlighting the performance of this new bio-composite material compared to other classical materials. The results were obtained by numerical simulation using EnergyPlus software. Firstly, the hygrothermal model was validated using experimental data. Afterward, the model was used to investigate the influence of moisture transport on indoor temperature, relative humidity, and energy consumption of a DPC building. The results indicate that mass transport through the DPC envelope significantly influences indoor relative humidity and building energy consumption, particularly during the summertime. On the contrary, the indoor temperature remains to be less influenced by mass transport through the building walls. Finally, the hygrothermal performances of DPC and conventional construction materials (Autoclaved Aerated Concrete, AAC) were compared in terms of thermal and hydric inertia, energy saving, and condensation risk. The results show that DPC significantly dampens and delays the temperature variation, mitigates relative humidity variations, and reduces cooling energy, especially in humid and semi-arid climates. Furthermore, DPC ensures that there is no risk of vapor condensation occurring on the envelope's surfaces.

Phage Resistance Reduced the Pathogenicity of Xanthomonas oryzae pv. oryzae on Rice.

Plants grow together with microbes that have both negative and positive impacts on the host, while prokaryotes are in turn also hosts for viruses, co-evolving together in a complex interrelationship. Most research focuses on the interaction of either bacterial pathogens interacting with the plant host, or the impact on viruses on their pathogenic bacterial hosts. Few studies have investigated the co-evolution of bacterial pathogens with their host plants as well as with their bacterial viruses. In this work, we aimed to identify the genes that were associated with both phage sensitivity and host pathogenicity of the bacterium Xanthomonas oryzae pv. oryzae (Xoo), which is the most important bacterial rice pathogen. Using the Tn5 transposon mutation technology, we created a library of Xoo strain C2 comprising 4524 mutants, which were subsequently tested for phage infectability. The phage infection tests showed that less than 1% of the mutants (n = 36) were resistant to phage infection, which was attributed to the Tn5 insertion in 19 genes. Interestingly, three out of 19 genes that conveyed resistance to the phage resulted in reduced pathogenicity to rice seedlings compared to the wild type. We identified three genes involved in both phage infection and bacterial virulence, which were studied by knockout mutants and complementation experiments. All of the three knockout mutants were resistant to infection by phage X2, while the complemented strains restored the susceptibility to the bacterial virus. Surprisingly, the genes are also essential for pathogenicity, which we confirmed by single knockout mutants corresponding to the Tn5 mutants. All three genes are involved in lipopolysaccharide synthesis, thus changing the cell envelope surface molecule composition. Our work shows a possible balance in terms of the connection between bacterial virulence and phage resistance, supporting the deployment of phages for the biocontrol of plant pathogens.

Immunogenicity of the Envelope Surface Unit of Human Endogenous Retrovirus K18 in Mice

The triggers for the development of multiple sclerosis (MS) have not been fully understood to date. One hypothesis proposes a viral etiology. Interestingly, viral proteins from human endogenous retroviruses (HERVs) may play a role in the pathogenesis of MS. Allelic variants of the HERV-K18 env gene represent a genetic risk factor for MS, and the envelope protein is considered to be an Epstein–Barr virus-trans-activated superantigen. To further specify a possible role for HERV-K18 in MS, the present study examined the immunogenicity of the purified surface unit (SU). HERV-K18(SU) induced envelope-specific plasma IgG in immunized mice and triggered proliferation of T cells isolated from these mice. It did not trigger phenotypic changes in a mouse model of experimental autoimmune encephalomyelitis. Further studies are needed to investigate the underlying mechanisms of HERV-K18 interaction with immune system regulators in more detail.

Study of the Convective Heat Transfer Coefficient of Different Building Envelope Exterior Surfaces

Convective heat transfer on the exterior surface of the building envelope is an important component for building energy consumption. The calculation of energy consumption depends on the convective heat transfer coefficient (CHTC) of the exterior surface of the envelope. The existing research does not fully consider the effects of the airflow field around the building on the CHTC of different envelope exterior surfaces. In this paper, the relationships between the CHTC and influence factors were investigated for the isolated building. Response surface methodology (RSM) and support vector machine (SVM) algorithms were integrated with the single building simulation to build the fitting formulas. Then, the fitting correlation between CHTC and different influencing factors was validated by the heating building simulation. The results showed that the CHTC of the building exterior surface was related to the wind velocity, wind direction and temperature difference. Additionally, the fitting formulas had good accuracy in calculating the CHTC under different conditions. The SVM algorithm (averaged error: 3.34%) performed slightly better than the RSM algorithm (averaged error: 4.84%).

Horizontal bearing capacity of composite bucket foundation in clay: A case study

Failure of offshore wind power structural system is an important research topic in many countries. Most previous researches focus on the tower failures and blade failures rather than foundation failure. Taking the 3 MW of the composite bucket foundation (CBF) in China as a case study, a comprehensive study of the horizontal bearing response of CBF were carried out by a centrifuge model test and a series of numerical simulations. Results show that the horizontal bearing capacity of CBF increase at first and then decrease with the increase of the existing vertical load in two-dimensional loading space. The relationship between bending moment and horizontal load in two-dimensional loading space is approximate linear. The aspect ratio has influence on the capacity envelopes peak in horizontal-vertical load loading space. Three-dimensional envelope surface is obtained, the results provide a basis for the design of CBF of offshore wind turbine.

Improving the indoor thermal environment in lightweight buildings in winter by passive solar heating: An experimental study

Traditional lightweight building envelopes with constant thermal properties are of small heat capacity and large thermal resistance. Lightweight building envelopes with variable thermal conductivity and variable equivalent specific heat capacity can promote passive solar heat gain for clean heating and improve the indoor thermal environment in winter. In this paper, a real-scale lightweight solar house integrated with flat gravity-assisted heat pipes and PCM (phase change material) was built up, and the indoor heating effects of four forms of the solar house were experimentally studied. The results showed that (1) the heat pipes efficiently transferred solar heat absorbed by the exterior surface of the south envelope into the indoor environment during the day and increased the average daytime indoor air temperature by 3.8°C, but this benefit was not proportional to the area of heat pipes. (2) The PCM effectively stored solar energy during the day and released heat to the indoor environment at night, and the daily range of indoor air temperature was reduced by 8.7°C, with only 81% mass and 33% volume of concrete block, respectively. (3) The solar house increased the effective proportion of solar energy for indoor heating from 8.7% to 57.5% in the form of DHP + PCM house.

Implementation of the Non-Associated Elastoplastic MSDPu Model in FLAC3D and Application for Stress Analysis of Backfilled Stopes

The multiaxial Mises-Schleicher and Drucker-Prager unified (MSDPu) criterion has been shown to exhibit several specific features compared to other yield and failure criteria, including a nonlinear mean stress dependency, influence of the Lode angle, use of independent uniaxial compressive and tensile strength values and absence of an apex (singularity) on the envelope surface in the negative stress quadrant. However, MSDPu has been seldom used in practice to solve geotechnical and geomechanical engineering problems mainly because it had not yet been fully implemented into three-dimensional (3D) numerical codes. To fill this gap, a 3D elastoplastic MSDPu formulation is developed and implemented into FLAC3D. The proposed MSDPu elastic-perfectly plastic (EPP) constitutive model is then validated against existing analytical solutions developed for calculating the stress and displacement distributions around cylindrical openings. The FLAC3D MSDPu-EPP model is then applied to evaluate the vertical and horizontal stress distributions in a three-dimensional vertical backfilled stope. The numerical results obtained with the MSDPu-EPP model are compared with those obtained with the Mohr-Coulomb EPP model, to highlight key features of the new formulation.