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Within the framework of the put forward hypothesis that energy costs of working movements of the links of racking stacker cranes are inextricably linked to the shape of the working area of the warehouse in which the crane operates, to reduce energy costs, it was pro-posed to use a rotating boom in the design of the stacker crane. With the help of program implementations of mathematical models of stacker cranes of traditional bicycle design and the proposed design with a rotating boom, it became possible to determine the average energy costs for all possible movements of loads of the same mass within the corresponding working areas of these designs. For this purpose, systems of differential equations in Cauchy form were developed, where dissipation of energy was taken into account. The total value of work of crane drives during acceleration and braking was determined. The latter were carried out with constant accelerations, and the movement after acceleration — with constant speeds. The developed simulation mathematical models of cranes of traditional design and the proposed design with a rotating boom allow to determine the energy costs in the drives when moving the crane links along the given trajectories. According to the criterion of average total energy costs, adopted for all possible combinations of movements within areas of the same capacity of one hundred square meters, the stacker crane of the proposed design has an advantage over the crane of traditional design. This makes it possible to significantly reduce energy costs when using such cranes in warehouses and hangars. It is reasonable to recommend the use of a stacker crane of the developed design in warehouses of round shape — it will allow to reduce significantly the energy costs when using such cranes in warehouses and hangars.

Although solar photovoltaic (PV) system costs have declined, capital cost remains a barrier to widespread adoption. Do-it-yourself (DIY) system designs can significantly reduce labor costs, but if they are not attached to a building structure, they require ground penetrating footings. This is not technically and economically feasible at all sites. To overcome these challenges, this study details systems designed to (1) eliminate drilling holes and pouring concrete, (2) propose solutions for both fixed and variable tilt systems, (3) remain cost effective, and (4) allow for modifications to best fit the user's needs. The ballast-supported foundations are analyzed for eight systems by proposing two separate ballast designs: one for a single line of post systems, and one for a double line of post systems, both built on a 4-kW basis. The results of the analysis found that both designs are slightly more expensive than typical in-ground concrete systems by 25% (assuming rocks are purchased at a landscaping company), but the overall DIY system's costs remain economically advantageous. Sensitivity analyses are conducted to show how modifications to the dimensions influence the weight of the system and thus change the economic value of the design, so users can trade dimensional freedom for cost savings, and vice versa. Overall, all wood-based PV racking system designs provide users with cost-effective and easy DIY alternatives to conventional metal racking, and the novel ballast systems presented provide more versatility for PV systems installations. [ABSTRACT FROM AUTHOR]

The prohibitive costs of small-scale solar photovoltaic (PV) racks decrease PV adoption velocity. To overcome these costs challenges, an open hardware design method is used to develop two novel variable tilt racking designs. These are the first stilt-mounted racking designs that allow for the manual change of the tilt angle from zero to 90 degrees by varying the length of cables. The racks are designed using the calculated dead, wind, and snow loads for Canada as a conservative design for most of the rest of the world. Structural capacities of the wooden members are then ascertained and the resisting bending moment, shear force, tensile force, and compressive force is calculated for them. A structural and truss analysis is performed to ensure that the racking design withstands the applicable forces. Moreover, the implications of changing the tilt angle on the wooden members/cables used to build the system are also determined. The systems offer significant economic savings ranging from one third to two thirds of the capital expenses of the commercially available alternatives. In addition, the racking designs are easy-to-build and require minimal manufacturing operations, which increases their accessibility. The stilt-mounted designs can be employed for agrivoltaic settings while allowing farm workers shaded, ergonomic access to perform planting, weeding, and harvesting. [ABSTRACT FROM AUTHOR]

The widespread use of racking stacker cranes is due to the spread of automated warehouses. Reduction of energy costs when using stacker cranes is one of the main directions of their improvement. The development of mathematical simulation models of stacker cranes allows to determine the energy costs of cargo movement at the stage of design and research. For a new design of the racking crane-stacker, having a rotary boom with a cargo carriage moving along it in the radial direction, a mathematical model in the form of a system of Lagrange differential equations of the second order has been developed. The system of differential equations took into account the energy losses according to the model of viscous friction in the moving links of the boom and the load carriage of the crane. For this purpose, when deriving the differential equations, the Rayleigh function was used, as well as analytical expressions of the potential and kinetic energies of the moving links of the crane, which were differentiated. With the help of typical blocks of the Russian simulation modeling system SimInTech, the obtained system of differential equations was realized in the form of a block diagram. The use of blocks of proportional-integral-differentiating regulators in the simulation model allowed to realize the principle of working out the given trajectory of movement of the crane links, and the numerical integration of the current powers of the boom and carriage drives allowed to determine the accumulated total energy consumption of the drives at a given displacement. The current values of drive powers were determined as products of moments and forces of drives on the speeds of the corresponding links of the boom and carriage. As an example, when running the simulation model, the time dependences of the coordinates of the boom and load carriage of the crane, as well as the moments and forces of the drives, power and work during the movement from a point with zero coordinates to a point with specified coordinates and back. The developed simulation mathematical model is intended to determine the energy costs in the drives of a new design crane with a rotating boom at given displacements of links, as well as, in the future, to verify the control algorithms.

Stacker cranes are widely used in automated warehouses. The actual task is to increase their energy efficiency and productivity. Simulation mathematical models are used for the solution of this problem at the stage of research and development works. We have developed a mathematical model of a rack stacker crane in long spatial displacements taking into account energy dissipation of linear coordinates of the cart and the cargo carriage. The model is a system of two second-order Lagrange differential equations. Partial derivatives of analytical expressions of kinetic and potential energies of the dynamic stacker crane system as well as dissipative Rayleigh function are used for derivation of the differential equations. Different values of dissipation coefficients for two linear coordinates of the stacker crane can be used. Using SimInTech we develop a simulation model of a conventional stacker crane based on the suggested system of differential equations and represented in the form of a block diagram. The developed simulation model is described and an example of its use is given. A complex model of a shelf stacker crane includes as a constituent part a procedure of determining time intervals of equivalent-accelerated motion of the links. Examples of time dependences of the crane bogie and cargo carriage coordinates, drive forces providing the set coordinate dependences, drives work and total work are given. The developed mathematical model of the stacker-crane can be used for the modelling of the processes of the cargo moving along the rack, its raising to the given height corresponding to the rack target cell, its lowering as well as for the estimation of the energy input of the crane.

Although solar photovoltaic (PV) system costs have declined, capital cost remains a barrier to widespread adoption. Do-it-yourself (DIY) system designs can significantly reduce labor costs, but if they are not attached to a building structure, they require ground penetrating footings. This is not technically and economically feasible at all sites. To overcome these challenges, this study details systems designed to (1) eliminate drilling holes and pouring concrete, (2) propose solutions for both fixed and variable tilt systems, (3) remain cost effective, and (4) allow for modifications to best fit the user’s needs. The ballast-supported foundations are analyzed for eight systems by proposing two separate ballast designs: one for a single line of post systems, and one for a double line of post systems, both built on a 4-kW basis. The results of the analysis found that both designs are slightly more expensive than typical in-ground concrete systems by 25% (assuming rocks are purchased at a landscaping company), but the overall DIY system’s costs remain economically advantageous. Sensitivity analyses are conducted to show how modifications to the dimensions influence the weight of the system and thus change the economic value of the design, so users can trade dimensional freedom for cost savings, and vice versa. Overall, all wood-based PV racking system designs provide users with cost-effective and easy DIY alternatives to conventional metal racking, and the novel ballast systems presented provide more versatility for PV systems installations.

The prohibitive costs of small-scale solar photovoltaic (PV) racks decrease PV adoption velocity. To overcome these costs challenges, an open hardware design method is used to develop two novel variable tilt racking designs. These are the first stilt-mounted racking designs that allow for the manual change of the tilt angle from zero to 90 degrees by varying the length of cables. The racks are designed using the calculated dead, wind, and snow loads for Canada as a conservative design for most of the rest of the world. Structural capacities of the wooden members are then ascertained and the resisting bending moment, shear force, tensile force, and compressive force is calculated for them. A structural and truss analysis is performed to ensure that the racking design withstands the applicable forces. Moreover, the implications of changing the tilt angle on the wooden members/cables used to build the system are also determined. The systems offer significant economic savings ranging from one third to two thirds of the capital expenses of the commercially available alternatives. In addition, the racking designs are easy-to-build and require minimal manufacturing operations, which increases their accessibility. The stilt-mounted designs can be employed for agrivoltaic settings while allowing farm workers shaded, ergonomic access to perform planting, weeding, and harvesting.

Open-source technological development is well-known for rapid innovation and providing opportunities to reduce costs and thus increase accessibility for a wide range of products. This is done through distributed manufacturing, in which products are produced close to end users. There is anecdotal evidence that these opportunities are heavily geographically dependent, with some locations unable to acquire components to build open hardware at accessible prices because of trade restrictions, tariffs, taxes, or market availability. Supply chain disruptions during the COVID-19 pandemic exacerbated this and forced designers to pivot towards a la carte-style design frameworks for critical system components. To further develop this phenomenon, a case study of free and open-source solar photovoltaic (PV) racking systems is provided. Two similar open-source designs made from different materials are compared in terms of capital costs for their detailed bill of materials throughout ten locations in North, Central and South America. The differences in economic optimization showed that the costs of wood-based racks were superior in North America and in some South American countries, while metal was less costly in Central and South America. The results make it clear that open hardware designs would be best to allow for local optimization based on material availability in all designs. [ABSTRACT FROM AUTHOR]

Vertical bifacial solar photovoltaic (PV) racking systems offer the opportunity for large-scale agrivoltaics to be employed at farms producing field crops with conventional farming equipment. Unfortunately, commercial proprietary vertical racks cost more than all types of conventional PV farm racking solutions. To overcome these cost barriers, this study reports on the development of a new wood-based PV racking design. The open-source design consists of a hinge mechanism, which reduces mechanical loading and enables wood to be used as the main structural material, and is the first of its kind. This open-source vertical wood-based PV rack is (i) constructed from locally accessible (domestic) renewable and sustainable materials, (ii) able to be made with hand tools by the average farmer on site, (iii) possesses a 25-year lifetime to match PV warranties, and (iv) is structurally sound, following Canadian building codes to weather high wind speeds and heavy snow loads. The results showed that the capital cost of the racking system is less expensive than the commercial equivalent and all of the previous wood-based rack designs, at a single unit retail cost of CAD 0.21. The racking LCOE is 77% of the cost of an equivalent commercial racking system using retail small-scale component costs, and is 22%, 34%, and 38% less expensive than commercial metal vertical racking, wood fixed tilt racking, and wood seasonal tilt racking costs, respectively. Overall, wooden vertical swinging PV racking provides users with a low-cost, highly available alternative to conventional metal vertical racking, along with a potential increase in energy yield in high wind areas thanks to its unique swinging mechanism. [ABSTRACT FROM AUTHOR]

• Retrofitting animal fencing for dual use for vertical-mounted monofacial PV racking. • Python-based Open Source Wind Load Calculator used for viability throughout the U.S. • Base shear force mapped for all fences for wind loads from 80 mph to 150. • Agrivoltaic system potential that as little as $0.035/kWh for racking on existing fencing. • Racking cost savings make fence-retrofit agrivoltaics a promising new technology. Popular agrivoltaic systems use photovoltaic (PV) farms for pasture grazing animals. In general, these agrivoltaic systems do not reduce the capital cost of a PV farm and in some cases can increase it. To overcome this challenge this study investigates the potential for retrofitting existing animal fencing on farms to have dual use for vertical-mounted monofacial PV racking. Specifically, this study catalogs types of fences and wind load calculations classified under Risk Category I are run through a new python-based Open Source Wind Load Calculator to determine the viability of fence-based racking throughout the U.S. The base shear force for all the fences are calculated for a range of wind loads from 80mph to 150mph (129 km/h to 241 km/h) and the results are mapped to indicate the number of PV modules between the vertical fence poles a fence can tolerate in a specific location. The results show the required fence type including post and battens in a given area for sheep, goats, pigs, cows, and alpaca to be used for agrivoltaics. Overall, at least one PV module between posts is acceptable indicating a new agrivoltaic system potential that as little as $0.035/kWh for racking on existing fencing. Although the yield for a vertical PV can range from 20 to 76 % of an optimized tilt angle depending on azimuth, the racking cost savings enable fence-retrofit agrivoltaics to often produce lower levelized cost electricity. Future work is necessary to determine the full scope of benefits of vertical PV agricultural fencing on a global scale. [ABSTRACT FROM AUTHOR]

This work presents the study of the effectiveness of different inert gases applied during racking to prevent oxygen uptake by wine. Inert gases were used for the purging of empty tanks and hoses before the start of each racking, as well as for blanketing in the full racked tank. After analyzing these operations with the different inert gases, the required volumes of each gas were optimized. The CO2:Ar (20:80) mixture proved to be the most effective for the complete purging of the empty tank, while CO2 was the most cost-effective gas. Purging the empty tank with 25% vessel volume gas was sufficient to achieve useful inerting with all the gases studied, as well as to maintain low levels of dissolved oxygen (DO) in the wine filling the tank. Applying 0.5 of vessel volume of Ar, CO2:Ar (20:80), and CO2 gases during blanketing allowed the headspace oxygen (HSO) of the racked tank to be protected throughout. During the racking of a white wine in a commercial winery, Ar showed the highest efficiency, compared to N2, for both the inerting of empty hoses and destination tank and for maintaining low levels of DO and HSO in the tank. [ABSTRACT FROM AUTHOR]

Advanced numerical models can be used to complement experimental results and further elucidate their findings. This is particularly true when certain scaled model "adjustments" are incorporated in the testing scheme to reduce the testing cost or schedule. This study conducts comprehensive finite element modeling to simulate large-scale shaking table tests conducted by Kim et al. (2023) [1] to evaluate the seismic performance of steel tunnels. The numerical model was calibrated by comparing its predictions with the experimental observations in the initial tests. The calibrated model was then validated by comparing its predictions with the results obtained from other test models and subjected to different input ground motions. The validated model was employed to comprehensively investigate the effects of the testing scheme parameters including the input motion time scaling, tunnel burial depth, and soil relative density. It was found that reducing the time scale factor during the tests led to decreased seismic responses. It was also found that the presence of overburden soil on top of the tunnel resulted in higher seismic bending moment values, and that higher overburden height increased both lateral and vertical soil pressures on the tunnel side walls and top slab. In addition, lateral soil distortion and tunnel deformations were found to be directly correlated with the overburden soil height. Furthermore, in the absence of overburden soil, there was a significant amplification in horizontal soil acceleration. The results demonstrated that lower-density sand bed experienced greater acceleration amplification and larger displacement, and the tunnel experienced larger lateral soil pressure and higher racking. Additionally, the results revealed that subjecting the same soil bed to several shaking tests affected its stiffness, and hence affected the test observations in the subsequent tests. This should be considered when planning shaking table tests. Finally, the strain values and racking ratios obtained from the numerical simulations and the shaking tests were in agreement with the values obtained from the FHWA procedure. • Used advanced models to simulate large-scale shaking tests, providing insights into steel tunnels' seismic performance. • Calibrated and validated numerical models against experimental data, ensuring accuracy in predicting seismic responses. • Investigated the effects of time scale factor, burial depth, and soil density on seismic responses. • Demonstrated overburden soil's impact on seismic bending moment, soil pressure, lateral displacement, and tunnel deformation. • Highlighted the amplification of horizontal soil acceleration without overburden soil and its impact on the tunnel behavior. • Studied sequential shaking effects on the soil beneath the tunnel, emphasizing soil stiffness degradation in test results. [ABSTRACT FROM AUTHOR]

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Although solar photovoltaic (PV) module costs have been declining aggressively there has been only modest capital cost improvements for the balance of systems (BoS) in general, and for racking in particular. For small-scale PV systems racking can make up the majority of the capital expenditures. To overcome this challenge, in this study a novel parametric mobile low-cost open source racking system is designed using open source software and validated with numerical modeling. The system is designed to use readily accessible vertically-mounted conduit and steel cables and be built with common hand tools so that it is easily replicable in remote areas and the developing world. It can be assembled and deployed in half an hour and easily dissembled and flat-packed for transport. The system can be fabricated for less than commercial racks and is completely customizable in terms of tilt angle and size. The racking system is designed to resist light to moderate wind loads consistent with everyday breezes rather than those commonly used for structural design which are based on extreme events; as it is assumed the racking system will be disassembled and stowed prior to an extreme wind event. • Small-scale photovoltaic (PV) systems racking is majority of capital expenditures • Novel parametric mobile low-cost open source racking system • Designed using open source software and validated with numerical modeling. • Vertically-mounted conduit and steel cables, built with common hand tools • Fabrication costs < commercial racks; completely customizable for tilt angle + size. [ABSTRACT FROM AUTHOR]

Fixed-tilt mechanical racking, consisting of proprietary aluminum extrusions, can dominate the capital costs of small-scale solar photovoltaic (PV) systems. Recent design research has shown that wood-racking can decrease the capital costs of small systems by more than 75% in North America. To determine if wood racking provides enough savings to enable labor to be exchanged profitably for higher solar electric output, this article develops a novel variable tilt angle open-source wood-based do-it-yourself (DIY) PV rack that can be built and adjusted at exceptionally low costs. A detailed levelized cost of electricity (LCOE) production analysis is performed after the optimal monthly tilt angles are determined for a range of latitudes. The results show the racking systems with an optimal variable seasonal tilt angle have the best lifetime energy production, with 5.2% more energy generated compared to the fixed-tilt system (or 4.8% more energy, if limited to a maximum tilt angle of 60°). Both fixed and variable wooden racking systems show similar LCOE, which is only 29% of the LCOE of commercial metal racking. The results of this study indicate that the novel variable tilt rack, whether used as a small-scale DIY project or scaled up to fulfill larger energy demands, provides both the lowest cost option even when modest labor costs are included and also may provide specific advantages for applications such as agrivoltaics. [ABSTRACT FROM AUTHOR]

Although small solar photovoltaic (PV) systems avoid most soft costs, they still have a relatively high $/W value due to racking costs. In order to fulfill the promise of small-scale plug-and-play solar, a do-it-yourself PV rack design is provided and analyzed here for six criteria: (1) made from locally-accessible renewable materials, (2) 25-year lifetime to match PV warranties, (3) able to be fabricated by average consumers, (4) able to meet Canadian structural building codes, (5) low cost and (6) that it is shared using an open-source license. The open-source wood-based fixed-tilt ground-mounted bifacial photovoltaic rack design evaluated here was found to be appropriate throughout North America. Economic analysis of the bill of materials showed the racking system ranges from 49% to 77% less expensive compared to commercial proprietary racking in Canada. The racking design, however, is highly dependent on the cost of lumber that varies widely throughout the world. Even for an absolute lower-cost design in Togo due to a lower fixed tilt angle and lower loads from lack of snow, it was not found to be economic because of the relatively high cost of wood. The recent volatile lumber market warrants local evaluation from those considering the use of the open-source design. This design, however, provides for a PV rack that can be manufactured with distributed means throughout most of the world enabling more equitable access to solar energy to support a circular bioeconomy. [ABSTRACT FROM AUTHOR]

Vertical bifacial solar photovoltaic (PV) racking systems offer the opportunity for large-scale agrivoltaics to be employed at farms producing field crops with conventional farming equipment. Unfortunately, commercial proprietary vertical racks cost more than all types of conventional PV farm racking solutions. To overcome these cost barriers, this study reports on the development of a new wood-based PV racking design. The open-source design consists of a hinge mechanism, which reduces mechanical loading and enables wood to be used as the main structural material, and is the first of its kind. This open-source vertical wood-based PV rack is (i) constructed from locally accessible (domestic) renewable and sustainable materials, (ii) able to be made with hand tools by the average farmer on site, (iii) possesses a 25-year lifetime to match PV warranties, and (iv) is structurally sound, following Canadian building codes to weather high wind speeds and heavy snow loads. The results showed that the capital cost of the racking system is less expensive than the commercial equivalent and all of the previous wood-based rack designs, at a single unit retail cost of CAD 0.21. The racking LCOE is 77% of the cost of an equivalent commercial racking system using retail small-scale component costs, and is 22%, 34%, and 38% less expensive than commercial metal vertical racking, wood fixed tilt racking, and wood seasonal tilt racking costs, respectively. Overall, wooden vertical swinging PV racking provides users with a low-cost, highly available alternative to conventional metal vertical racking, along with a potential increase in energy yield in high wind areas thanks to its unique swinging mechanism.

This work presents the study of the effectiveness of different inert gases applied during racking to prevent oxygen uptake by wine. Inert gases were used for the purging of empty tanks and hoses before the start of each racking, as well as for blanketing in the full racked tank. After analyzing these operations with the different inert gases, the required volumes of each gas were optimized. The CO2:Ar (20:80) mixture proved to be the most effective for the complete purging of the empty tank, while CO2 was the most cost-effective gas. Purging the empty tank with 25% vessel volume gas was sufficient to achieve useful inerting with all the gases studied, as well as to maintain low levels of dissolved oxygen (DO) in the wine filling the tank. Applying 0.5 of vessel volume of Ar, CO2:Ar (20:80), and CO2 gases during blanketing allowed the headspace oxygen (HSO) of the racked tank to be protected throughout. During the racking of a white wine in a commercial winery, Ar showed the highest efficiency, compared to N2, for both the inerting of empty hoses and destination tank and for maintaining low levels of DO and HSO in the tank.

This research aimed to employ stacking and racking analysis techniques in the Rasch model to measure the hydrolysis conceptual changes of students taught by the process-oriented guided inquiry learning (POGIL) model in the context of socio-scientific issues (SSI) with the pretest-posttest control group design. Such techniques were based on a person- and item-centered statistic to determine how students and items changed during interventions. Eleventh-grade students in one of the top-ranked senior high schools in the eastern part of Indonesia were involved as the participants. They provided written responses (pre- and post-test) to 15 three-tier multiple-choice items. Their responses were assessed through a rubric that combines diagnostic measurement and certainty of response index. Moreover, the data were analyzed following the Rasch Partial Credit Model, using the WINSTEPS 4.5.5 software. The results suggested that students in the experimental group taught by the POGIL approach in the SSI context had better positive conceptual changes than those in the control class learning with a conventional approach. Along with the intervention effect, in certain cases, it was found that positive conceptual changes were possibly due to student guessing, which happened to be correct (lucky guess), and cheating. In other cases, students who experienced negative conceptual changes may respond incorrectly due to carelessness, the boredom of problem-solving, or misconception. Such findings have also proven that some students tend to give specific responses after the intervention in certain items, indicating that not all students fit the intervention. Besides, stacking and racking analyses are highly significant in detailing every change in students’ abilities, item difficulty levels, and learning progress.

• A detailed modeling of solar PV racking geometry is reported. • Equivalent tensegrity racking is derived for real-world deployment. • Bifacial performance is simulated with Radiance Optical ray-trace method. • Tensegrity racking enhances the rear irradiance for bifacial PV by 50% or more. • The rear surface irradiance varies with day-hour and module position. Bifacial PV has emerged as the de-facto choice for utility-scale ground-mounted PV arrays due to their ability to collect solar irradiance from both the front and rear surfaces. However, conventional racking structures were not designed to minimize shadowing of the rear surface since they were developed with only monofacial panels in mind. In this study, we explore the utilization of tensegrity racking structures as an alternative to conventional PV rackings. Tensegrity structures are comprised of rods and cables that achieve structural integrity while minimizing mass, form factor, and possibly cost. In order to explore the potential of tensegrity structures, Radiance optical ray-tracing simulation was used to compare the bifacial performance between the two types of racking solutions. The simulation model was built using the on-site array configurations and the racking geometry obtained from a commercial array that features both monofacial and bifacial panels. High-level results show that the racking and mounting structure contribute to about 18% shading. With other parameters kept unchanged, the tensegrity structure is found to enable up to 60% increase in rear surface irradiance by mainly reducing the rear surface shading caused by the on-site racking structures. The work, through its novel approach of detailed modeling of racking geometry, demonstrates the potential of tensegrity racking structures for bifacial PV arrays. [ABSTRACT FROM AUTHOR]

Fixed-tilt mechanical racking, consisting of proprietary aluminum extrusions, can dominate the capital costs of small-scale solar photovoltaic (PV) systems. Recent design research has shown that wood-racking can decrease the capital costs of small systems by more than 75% in North America. To determine if wood racking provides enough savings to enable labor to be exchanged profitably for higher solar electric output, this article develops a novel variable tilt angle open-source wood-based do-it-yourself (DIY) PV rack that can be built and adjusted at exceptionally low costs. A detailed levelized cost of electricity (LCOE) production analysis is performed after the optimal monthly tilt angles are determined for a range of latitudes. The results show the racking systems with an optimal variable seasonal tilt angle have the best lifetime energy production, with 5.2% more energy generated compared to the fixed-tilt system (or 4.8% more energy, if limited to a maximum tilt angle of 60°). Both fixed and variable wooden racking systems show similar LCOE, which is only 29% of the LCOE of commercial metal racking. The results of this study indicate that the novel variable tilt rack, whether used as a small-scale DIY project or scaled up to fulfill larger energy demands, provides both the lowest cost option even when modest labor costs are included and also may provide specific advantages for applications such as agrivoltaics.

Although small solar photovoltaic (PV) systems avoid most soft costs, they still have a relatively high $/W value due to racking costs. In order to fulfill the promise of small-scale plug-and-play solar, a do-it-yourself PV rack design is provided and analyzed here for six criteria: (1) made from locally-accessible renewable materials, (2) 25-year lifetime to match PV warranties, (3) able to be fabricated by average consumers, (4) able to meet Canadian structural building codes, (5) low cost and (6) that it is shared using an open-source license. The open-source wood-based fixed-tilt ground-mounted bifacial photovoltaic rack design evaluated here was found to be appropriate throughout North America. Economic analysis of the bill of materials showed the racking system ranges from 49% to 77% less expensive compared to commercial proprietary racking in Canada. The racking design, however, is highly dependent on the cost of lumber that varies widely throughout the world. Even for an absolute lower-cost design in Togo due to a lower fixed tilt angle and lower loads from lack of snow, it was not found to be economic because of the relatively high cost of wood. The recent volatile lumber market warrants local evaluation from those considering the use of the open-source design. This design, however, provides for a PV rack that can be manufactured with distributed means throughout most of the world enabling more equitable access to solar energy to support a circular bioeconomy.

• Open source PV racking to reduce cost in utility scale ground mount systems. • Modules fastened to graded land covered in shotcrete with basic mounting hardware. • Open source V-shaped design, bill of materials, and cost comparison. • Northern latitude with low concentration reflector and equator designs. • Racking costs reduced 18–22% at low latitudes. Relentless cost declines in solar photovoltaic (PV) modules have radically reduced system costs, but the result is that racking costs have become more important. In this study a new open source racking method using earth and shotcrete-based ground mounts is investigated in two geographic regions: (1) Boa Vista, Brazil, where PV rows have an optimized shallow tilt angle and can be close-packed and (2) Kingston, Canada, where racks can make use of low concentration in the required inter-row spacing. Models are developed for both locations with single, double and triple vertical stacked shotcrete-based ground-mounted PV racking systems. Using these models bills of materials and energy simulations are produced to provide a cost benefit analysis specifically for the shotcrete racks. The results show that for utility-scale PV systems near the equator, a shotcrete racking system could reduce racking costs by 18–22% from the least expensive conventional racking and as much as 47% reduction for more expensive commercial racking. Economics is less clear for shotcrete-based racking at higher latitudes that incorporate low-concentration reflectors as they can be both lower and higher costs than conventional racking, but would be expected to produce at least 18% more electricity per installed Watt. Overall this novel racking concept was found to be promising, particularly for desert regions where it could reduce soiling losses. The results of this study indicate a need for future work to fully evaluate the potential of shotcrete racking to reduce solar electricity costs at the utility scale. [ABSTRACT FROM AUTHOR]

• Moment live load distribution factor (LLDF) predictions of AASHTO LRFD BDS including skew correction factors were, in general, conservative as compared to field measurements. AASHTO shear LLDFs were very conservative for all girders when compared to field measurements. • Analysis results showed that seasonal temperature changes were sufficient to create measurable superstructure in-plane rotations. Skewed superstructures were observed to rotate towards obtuse and acute corners for negative and positive temperature changes, respectively. • Increasing skew angles increased displacements at bearings in the bridge transverse direction. • For all cases, transverse bearing displacements were markedly greater than longitudinal ones. This has a special significance in typical bearing design where transverse bearing displacements are usually ignored. • Using a mix of fixed and expansion bearings over the same pier substantially reduces transverse bearing displacements and racking under temperature changes. High skew in bridges alters live load distribution and creates performance issues such as deck cracking, superstructure in-plane (horizontal) displacements and bearing distress. In-plane superstructure displacements, also called racking, are particularly important as they cause misalignments of superstructure and approach slabs, stress bearings and expansion joints. This study had two objectives: to evaluate live load distribution in skewed bridges and to understand how skew influences in-plane superstructure displacements. The effect of bridge design details on live load distribution and in-plane superstructure displacements was assessed through parametric studies on highly skewed bridges. A three-span, steel girder-concrete deck bridge with a 47-degree skew was load tested. Load test results were employed to validate finite element analyses that were used to understand the impact of varying skew angle, bridge features and bearing fixity on live load distribution and in-plane superstructure displacements. The ability of the American Association of Highway and Transportation Officials Load and Resistance Factor Design Bridge Design Specifications (AASHTO LRFD BDS) to accurately capture live load distribution for steel girder bridges was evaluated. Field test results, consisting of girder bending and vertical shear strains measured through strain gages strategically located on one of the exterior spans, and parametric studies showed that AASHTO LRFD BDS predicted shear and moment distribution very conservatively and closely, respectively. Seasonal temperature changes were sufficient to create in-plane (horizontal) superstructure displacements. These displacements caused the superstructure to rotate towards obtuse and acute corners for negative and positive temperature changes, respectively. Larger skew angles led to greater transverse (i.e., perpendicular to bridge longitudinal axis) displacements at girder bearings. Longitudinal (i.e., parallel to bridge longitudinal axis) displacements were consistently smaller than transverse displacements and were not affected by skew. Mixed bearing fixity arrangements, with both fixed and expansion bearings over the same pier, limited superstructure transverse in-plane displacements. [ABSTRACT FROM AUTHOR]

Transferring wine is a common operation in most of the wineries in the world that depends mainly on the equipment and materials used. These contributions are widely unknown, and their knowledge is of vital importance to controlling the winemaking process. This work presents the results of characterizing the oxygen supply due to the use of hoses of different materials (Butyl Rubber, IIR; Nitrile Butadiene Rubber, NBR; Ethylene Propylene Diene Monomer rubber, EPDM; Ultra-high-molecular-weight polyethylene, UHMW; Natural Rubber, NR), dimensions (DN32; DN50), connectors (DIN 11851, Tri-CLAMP) with gaskets of different materials (NBR; EPDM; Fluorocarbon, FKM/FPM; silicone rubber, Q/VMQ; Polytetrafluoroethylene, PTFE). In addition, the use of different inert gases (N2, CO2, Ar, N2 + CO2 and Ar + CO2) for air purging of hoses and tanks, as well as for ullage blanketing during tank-to-tank racking, and their economic impact were studied. The results indicated that the IIR hoses had the least amount of O2 added to the liquid and that the Tri-clamp connectors were generally more airtight, with the FKM seals standing out. The most recommended inert gas was CO2 when the type of wine allows it, N2 being the most recommended in any case. When all these recommendations were used together the addition of O2 during tank-to-tank racking was drastically reduced.

Highlights • Developed a closed-form solution for the seismic racking of rectangular tunnels. • Developed closed-form solutions for the seismic rocking and racking profile. • These are built over the simple concept of an elastic block subjected to pure shear. • Developed solutions prove to be accurate when compared to finite-element results. • These solutions enhance previous closed-form expressions derived for circular tunnels. Abstract Current design methodologies for underground structures subjected to earthquake action are based on closed-form solutions of the so-called racking coefficient, which relates the soil free-field distortion deformation to the structure distortion deformation. Existent closed-form expressions for this racking coefficient are derived for circular tunnel geometries embedded in an elastic and homogeneous medium, while expressions for rectangular geometries are based on analogies of the circular case. In this paper, a new and intuitive methodology derived from first principles to obtain a closed-form expression for the racking coefficient for rectangular-like tunnel geometries buried at a sufficient depth is presented, and it is shown that it provides a good fit to finite element analyses results. Similarly, a procedure to obtain closed-form expressions for the rocking rotation of the structure, and the racking deformation profile at different distances from the soil-tunnel interface is presented. [ABSTRACT FROM AUTHOR]

Highlights • Detailed finite element analysis of wood-frame walls. • Parametric models to calculate the load resistances of wood-frame walls. • Addresses several critical variables that can significantly influence the load resistances. • Modification factors proposed for calculating the load resistances. Abstract In a recent study by the author, the in-plane and out-of-plane wind load resistances of wood-frame walls were evaluated by using detailed finite element analysis. The analyses were performed by varying several design parameters and the effects of these parameters on the resistances were demonstrated. Based on the simulated responses, two parametric models were developed to calculate the in-plane and out-of-plane wind load resistances of wood-frame walls considering several design variables that affect the response of the walls significantly. However, the number of variables that can influence the resistances of wood-frame walls are numerous, and hence, it was very difficult to consider all the variables in the developed parametric models. In this study, several identified variables are considered which may produce different responses than those obtained from the parametric models developed. The effects of these variables were not considered while developing the parametric models. The study reported herein performs rigorous finite element analyses to address the influence of those unaccounted for variables and proposes modification factors to be used in the developed parametric models. [ABSTRACT FROM AUTHOR]

For practical calculations, the ovaling and racking deformations on buried structures are estimated by estimating the maximum shear strain (γmax) in imperforated ground using vertically incident shear waves (Vs). The relationship between maximum shear strain (γmax)and depth in a uniformly elastic half-space is a function of shear-wave velocity in the uniform medium and acceleration history in free field. In this study, the relationship between the distribution of γmax in elastic half space and in layered medium is examined by supposing that the travel time of shear waves from the free boundary to a depth of interest in a layered medium is equal to d/Vs. Different variety of strong ground motion time histories and three Vs profiles are used for analyses. The effect of nonlinear material response to shearing was investigated by using the method of equivalent linearization. [ABSTRACT FROM AUTHOR]

The R-F method is commonly implemented in design practice to evaluate the response of rectangular tunnels subjected to ground seismic shaking in the transversal direction. The efficiency of the method depends significantly on the so-called R-F relations, which correlate the flexibility ratio, F , expressing the soil to tunnel relative stiffness, with the racking ratio, R , that is used to account for the soil-tunnel interaction effects in the evaluation of the seismic racking distortion of the tunnel and subsequently in the evaluation of the seismic lining forces. This study presents a set of new R-F relations that were developed for a wide range of rectangular tunnels based on a comprehensive set of numerical parametric analyses, conducted to elaborate on the experimentally and numerically observed coupled racking-rocking response of this type of structures during transversal ground shaking. The new R-F relations account for the dynamic soil-tunnel interaction effects, as well as for the inherent effect of the rocking response of the tunnel section on the numerically computed racking ratios. Additionally, the study provides insights on the rocking response of the rectangular tunnels during shaking, by quantifying this response on the basis of normalized sectional rotation-flexibility ratio ( θ / γ ff - F ) relations. The efficiency of the R-F method, when the new R-F relations are used, is examined by comparing its predictions, in terms of seismic bending moment at critical sections of the tunnel lining, with relevant results of rigorous dynamic analyses. The predictions of the ‘improved’ R-F method are compared very well with the full dynamic analysis results, especially for the cases of rigid tunnels compared to the surrounding ground. Along these lines, the proposed relations may be used in practice, improving the accuracy of the R-F method in common engineering projects. [ABSTRACT FROM AUTHOR]

The present financial crisis is imposing shipbuilders to reduce costs and construction times in order to prevent orders cutback. In yacht design studios, based on improved aesthetics, this goal cannot be accomplished by simply skimping internal and/or external furnishing, but it must be achieved by reducing weights and costs of structural components, without compromising the structural strength of the super yacht. In this scenario, superstructure scantling is becoming the most critical aspect of structural design as they are built by using materials, like aluminum light alloy, which have low mechanical characteristics. The actual trend of having very big openings on the hull sides, because traditional windows have been drastically enlarged to offer suggestive landscapes to the owners and their guests, further worsens the problem. Furthermore, the aforementioned cost and weight cutback is achieved by reducing beam scantling dimensions and plate thicknesses to the minimum imposed by the Classification Society Rules; this trend might became very dangerous if loads acting on the yacht are not thoroughly assessed during the preliminary design stage. In this paper, the structural response of aluminum light alloy superstructures is studied by a finite element approach, coupled with static and dynamic loads imposed by the Classification Society Rules, with particular attention related to the buckling phenomena that occurs to slender stiffeners around windows. [ABSTRACT FROM AUTHOR]

A numerical parametric study was conducted on diverse soil-rectangular tunnel systems, aiming to shed light on critical response characteristics of rectangular tunnels subjected to transversal ground shaking. Salient parameters that affect the dynamic response, such as: (i) the soil-tunnel relative stiffness and interface properties, (ii) the shape, dimensions and burial depth of the tunnel section, (iii) the soil deposit characteristics, and (iv) the input motion characteristics, were accounted for in this study. This paper summarizes the key findings of this investigation, focusing on the complex deformation modes of the tunnels during shaking, the dynamic earth pressures and the soil dynamic shear stresses developed around the tunnel, and the dynamic lining forces. The numerical results indicated a combined racking-rocking deformation pattern for the tunnels during shaking, while inward deformations of the slabs and the side-walls were also observed for flexible tunnels, when soil inelasticity was encountered. To quantify the racking deformation of rectangular tunnels, a series of numerical racking ratio - flexibility ratio ( R-F ) relations were developed and compared with existing analytical and empirical ones. The rocking response of rectangular tunnels was quantified by means of dimensionless relations ( θ / γ ff -F ), similar to the R-F relations. The soil-tunnel relative stiffness, the interface characteristics and the soil yielding affected significantly the above relations, as well as the dynamic earth pressures, the soil dynamic shear stresses and the dynamic forces developed on the lining during shaking. The presented results lead to a better understanding of the seismic response of rectangular tunnels in soft soil, while the proposed relations contribute towards the improvement of the R-F analysis method. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to provide a technical and economic evaluation of the value of the RepRap as an entry-level 3-D printer in the developing world and provide a cost effective solar photovoltaic (PV) racking solution to better serve the developing world and aid in the acceleration of their economic and socioeconomic growth. A customizable open-source PV racking concept is designed, prototyped for three types of modules, constructed into systems, and outdoor tested under extreme conditions for one year. An economic analysis is provided along with a technical evaluation of the system, which found the proposed racking system can be successfully printed with RepRap 3-D printers and saves between 85% and 92% from commercially available alternatives depending on the plastic used for printing. In addition, the plastic parts proved able to withstand some of the harshest outdoor conditions and due to the free and open-source nature of the designs, it allows the system to be adapted to custom applications in any region in the world more easily than any commercial alternatives. The results indicate that the 3-D printable X-wire solar photovoltiac racking system has the potential to aid in the acceleration of solar deployment in the developing world by providing a low cost PV racking solution. [ABSTRACT FROM AUTHOR]