Comparing Open Data Repositories

Open Data is one of the main concepts of Open Science, which has the purpose to make scientific research artifacts accessible for everyone. Open data provides recommendations and practices to get access and use data from scientific researches, in a free, permanent, citable, auditable and interchangeable way. To facilitate the data management, it is important to store them in a repository. Considering this context, this paper provides a comparison among five known open data repositories. We performed the comparison taking into account a set of criteria, such as, data format constraints, digital identifier, versioning of published datasets, curators of data collections, metadata schema, versioning and exportation, storage limit, paid services, redundancy and preservation, access controls and APIs. We present results and discussions, in terms of such criteria.

Energy Evolution and Water Immersion-Induced Weakening Mechanism in the Sandstone Roof of Coal Mines

The instability of underground spaces in abandoned coal mines with water-immersed rocks is one of the main hazards hindering the geothermal energy utilization and ecological restoration of post-mining areas. This study conducted graded cyclic loading-unloading tests of five groups of sandstone samples with different water contents. The evolution laws of input, elastic, dissipated, damping, and plastic energies were explored in detail, taking into account the damping effect. The normalized plastic energy was used to characterize the damage evolution of sandstone samples, which failure modes were analyzed from both macroscopic and microscopic perspectives. The X-ray diffraction technique and scanning electron microscopy were used to reveal the softening mechanism of sandstone's strength and elastic energy storage limit. The results showed that the graded cyclic loading's input, elastic, and dissipated energies increased gradually. The elastic energy share first increased and then stabilized, while dissipated energy share variation had the opposite trend. In each cycle, the input energy was primarily stored in the form of elastic energy, while the dissipated energy was mainly used to overcome the damping of sandstone. When the normalized number of cycles approached unity, the plastic energy share sharply increased, while that of the dampening energy featured an abrupt drop. Such change indicated an inevitable instability failure of the water-bearing sandstone. As the water content increased, the pore water exhibited more substantial lubrication, water-wedging, and dissolution effects on mineral particles. As a result, the latter obtained a round form, and the elastic energy storage limit of the sandstone decreased. When the water content was increased, the damage factor of sandstone after the same number of cycles increased at a relatively higher rate, and there was a transition of failure mode from brittle to ductile.

Application of Regenerative Braking with Optimized Speed Profiles for Sustainable Train Operation

This paper presents a method for synergizing the energy-saving strategies of integrated coasting and regenerative braking in urban rail transit operations. Coasting saves energy by maintaining motion with propulsion disabled, but it induces longer travel time. Regenerative braking captures and reuses the braking energy of the train and could shorten travel time but reduces the time available for coasting, indicating a tradeoff between the two strategies. A simulation model was developed based on fundamental kinematic equations for assessing sustainable train operation with Wayside Energy-Saving Systems (WESSs). The objective of this study is to optimize speed profiles that minimize energy consumption, considering the train schedule and specifications, track alignment, speed limit, and the WESS parameters such as storage limit and energy losses in the transmission lines. The decision variables are the acceleration at each time step of the respective motion regimes. Since the study optimization problem is combinatorial, a Genetic Algorithm was developed to search for the solution. A case study was conducted which examined various scenarios with and without WESS on a segment of an urban rail transit line to test the applicability of the proposed model and to provide a platform for the application of ideas developed in this study. It was determined that synergizing the energy-saving strategies of coasting and regenerative braking yielded the greatest efficiency of the scenarios examined.

Rapid and Non-Destructive Monitoring of Moisture Content in Livestock Feed Using a Global Hyperspectral Model

The dry matter (DM) content of feed is vital in cattle nutrition and is inversely correlated with moisture content. The established ranges of moisture content serve as a marker for factors such as safe storage limit and DM intake. Rapid changes in moisture content necessitate rapid measurements. A rapid and non-destructive global model for the measurement of moisture content in total mixed ration feed and feed materials was developed. To achieve this, we varied and measured the moisture content in the feed and feed materials using standard methods and captured their images using a hyperspectral imaging (HSI) system in the spectral range of 1000–2500 nm. The spectral data from the samples were extracted and preprocessed using seven techniques and were used to develop a global model using partial least squares regression (PLSR) analysis. The range preprocessing technique had the best prediction accuracy (R2 = 0.98) and standard error of prediction (2.59%). Furthermore, the visual assessment of distribution in moisture content made possible by the generated PLSR-based moisture content mapped images could facilitate precise formulation. These applications of HSI, when used in commercial feed production, could help prevent feed spoilage and resultant health complications as well as underperformance of the animals from improper DM intake.

Energy Accumulation and Dissipation of Coal with Preopening under Uniaxial Loading

Energy accumulation and dissipation play an important role during the entire process of rock failure. Some flaws, such as preexisting holes, will influence energy accumulation and dissipation. In order to investigate the energy evolution of coal specimen with preexisting holes under uniaxial compression through numerical approaches, the particle simulation method was used in numerical simulations. In this paper, the energy evolution of coal specimen was theoretically analyzed, and the influence of different hole arrangement, such as diameter, spacing, angle, and number, on the evolution characteristics of energy was also discussed. At the same time, the arrangement of the artificial boreholes for preventing the rockburst was explored. The results show that, compared with the intact coal specimen, the change of diameter, spacing, angle, and the number of holes weakened the coal specimen’s capacity to store energy and release strain energy. When the diameter, the vertical distance, and relative angle of preexisting holes were 15 mm, 10∼15 mm, and 60°, respectively, the energy storage limit reached optimal value. For arrangement of the artificial boreholes, the diameter, spacing, and angle can be designed on the basis of those optimal values. This study has a guiding significance in designing the arrangement of the artificial boreholes for mitigation of rockburst.

Study on Energy Release of Surrounding Rock under the Multiple Unloading Disturbance during Tunnel Excavation

During excavation of deep rock, the release of strain energy plays an important role in geologic hazards caused by excavation. However, in the previous studies, the influence of transient unloading of in situ stress caused by blasting excavation has been ignored, and the blasting excavation of a tunnel is regarded as a single blast process. In this paper, the dynamic adjustment process of strain energy and the energy storage limit of surrounding rocks caused by transient unloading of in situ stress under elastic conditions were firstly analyzed. Then, the brittle-ductile-plastic transition model based on the Hoek–Brown strength criterion was simulated in FLAC3D. Finally, the dynamic release process of strain energy of surrounding rocks caused by multiple unloading disturbances was analyzed during the excavation of 2# Underground Laboratory of Jinping II Hydropower Station employing the newly proposed index, energy release coefficient (ERC). Results show that the strain energy of surrounding rock masses firstly decreases, then increases, next reduces, and finally stabilizes under the transient unloading of in situ stress. In the process of dynamic change of strain energy, when the strain energy exceeds its storage limit, a large amount of strain energy will be released and thus will lead to damage of the surrounding rock masses. Because the cut holes and the first circle of breaking holes are far away from the final excavation boundary, the unloading disturbance to the strain energy of surrounding rock masses is small. Furthermore, the energy release of surrounding rock masses is mainly caused by the unloading of the last circle of breaking holes and perimeter holes, and the closer to the final excavation boundary, the more intense the energy release.

Rockburst Identification Method Based on Energy Storage Limit of Surrounding Rock

Rockbursts are one of the prominent problems faced by deep underground engineering. Not only do they affect the construction progress, but they also threaten the safety of construction personnel and equipment, and may even induce earthquakes. Therefore, the prediction of rockbursts has very important engineering significance for the excavation of deeply buried tunnels. In this paper, a new indicator for stability and optimization evaluation of hard, brittle surrounding rock under high geo-stresses, namely the minimum energy storage limit of surrounding rock induced by transient unloading, is proposed. In addition, the time for erecting support for tunnel excavation in the rockburst area and the impact of excavation dimensions on rockburst are investigated. The results show that transient unloading during the tunnel excavation process will reduce the energy storage limit of the rock mass. When the strain energy density of the local surrounding rock exceeds the minimum energy storage limit of the rock mass, the rock mass energy is suddenly released, and rockburst occurs. Rockburst is most likely to occur at 0.42–0.65 D away from the working face. The increasing length of a round adopted in high geo-stress areas will make the surrounding rock unstable and increase the probability of rockburst.

Visualization of Food Bank/Agency Distribution

Food banking generates large amount of structured and unstructured data typically stored and reported in spreadsheet format. The growing scale of data storage limit the effectiveness of traditional spreadsheet data exploration methods used by decision makers. Spreadsheets are generally convenient and easy to use for processing data, but less so for big data stores due to limitations such as capacity, computing performance, interactivity, and plotting capability. Visual analytics was proposed as an approach to improve information seeing using data provided by the Food Bank of Central and Eastern North Carolina. SAS Visual Analytics was used to generate interactive dashboards that included a geo map based on spreadsheet data for agency food distribution. Feedback from the Food Bank’s management indicate substantial interest for visual analytics as a decision aid. A formal study is planned to evaluate decision-making performance with the dashboard in comparison to existing food bank methods.