Stream WatDiv - A Streaming RDF Benchmark

Modern applications are required to process stream data which are semantically tagged. Sometimes static background data interlinked with stream data are also needed to answer the query. To meet these requirements, streaming RDF processing (SRP) engines emerged in recent years. Although most SRP engines adopt the same streaming RDF data model in which a streaming RDF triple is an RDF triple annotated with a timestamp, there is no standard query language, which means every engine has their own language syntax. In addition, these engines are quite primitive, different engines support limited and different query operation sets. What's more, they are fragile in face of complex query, high stream rate or large static dataset. This poses a lot of challenges to evaluate the SRP engines. In our work, we show that previous streaming RDF benchmarks do not have a sufficient workload to understand engine's performance. The queries in those workloads are either not executable on existing engines, or very limited in terms of number. The goal of this work is to propose a benchmark which provides diversified datasets and workloads. In our work, we extend WatDiv to generate streaming data and streaming query, and propose a new streaming RDF benchmark, called Stream WatDiv. WatDiv is an RDF benchmark designed for diversified stress testing of RDF data management engines. It introduces a collection of query features, which is used to assess the diversity of dataset and workloads. Through proper data schema design and query generation, WatDiv shows a good coverage of values of these query features. We demonstrate the feasibility of applying the same idea in streaming RDF domain. Stream WatDiv benchmark suits contain a data generator to generate scalable streaming data and static data, a query generator to generate scalable workloads, and a testbed to monitor the engine's output. We evaluate two engines, C-SPARQL and CQELS, and measure the correctness of engine output, latency and memory consumption. The findings contain two parts. First, we validate the result related to these two engines in previous works. (1) CQELS is more robust and efficient than C-SPARQL at processing streaming RDF queries in most cases. (2) increasing streaming rate and integrating static data will significantly degrade C-SPARQL's performance, while CQELS is marginally affected. (3) C-SPARQL is more memory-efficient than CQELS. Second, the diversity of Stream WatDiv workloads helps detect engines' issues that are not captured before. Queries can be grouped into different types based on the query features. These types of queries can be used to evaluate a specific engine features. (1) Triple pattern count of a query influences C-SPARQL's performance. (2) Both C-SPARQL and CQELS show a significant latency increase when the query has larger result cardinality. (3) Neither of these two engines are biased toward processing linear, star or snowflake queries. (4) CQELS is more efficient at handling queries with variously selective triple patterns, while C-SPARQL performs better for queries with equally selective triple patterns than queries with variously selective triple patterns

Mechanical Properties of Recycled Aggregate Concrete Modified by Nano-particles

In this study, different nano-particles were used to modify recycled aggregates concrete (RAC) containing recycled clay brick aggregates (RCBAs) to improve the RAC properties. Two stages of experimental works were performed. In the first stage, various nano-particle mixtures produced by different mixing methods, i.e. the use of surfactant and ultrasonication, were examined by optical microscope to evaluate the dispersion of the nano-particles in water liquid. The nano-particles modified cement mortar specimens were further evaluated by flexural tensile test to check how these mixing methods affect the properties of the nano-particle modified cement mortar. In the second experimental stage, the effects of four replacement ratios of recycled aggregates, three type of nano-particles, two mixing methods of RAC, additional surfactant and ultrasonication process used in the mix of nano-particle liquid, and the dosages of the nano-particles on the workability, compressive and split tensile properties of the nano-particle modified RAC were investigated

Mechanical Properties of Nanostructured CoCrFeNiMn High-Entropy Alloy (HEA) Coating

An equiatomic CoCrFeMnNi high-entropy alloy (HEA) thin film coating has been successfully developed by high-vacuum Radio Frequency (RF) magnetron sputtering. The deposition of a smooth and homogenous thin film with uniformly distributed equiaxed nanograins (grain size ~ 10 nm) was achieved through this technique. The thin film coating exhibits a high hardness of 6.8 ± 0.6 GPa, which is superior compared to its bulk counterpart owing to its nanocrystalline structure. Furthermore, it also shows good ductility through nanoindentation, which demonstrates its potential to serve as an alternative to traditional transition metal nitride or carbide coatings for applications in micro-fabrication and advanced coating technologies

Preparation Method of Co 3

Co3O4 nanoparticles were fabricated by a novel, facile, and environment-friendly carbon-assisted method using degreasing cotton. Structural and morphological characterizations were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The component of the sample obtained at different temperatures was measured by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Nitrogen adsorption and desorption isotherms were utilized to reveal the specific surface areas. The formation mechanism of Co3O4 nanoparticles was also proposed, demonstrating that the additive degreasing cotton played an indispensable role in the process of synthesizing the sample. The resultant Co3O4 sample calcined at 600°C exhibited superior electrochemical performance with better specific capacitance and long-term cycling life, due to its high specific surface areas and pores structures. Additionally, it has been proved that this facile synthetic strategy can be extended to produce other metal oxide materials (e.g., Fe3O4). As a consequence, the carbon-assisted method using degreasing cotton accompanied a promising prospect for practical application

Compressive performance of fiber reinforced polymer encased recycled concrete with nanoparticles

Nanomaterials have been used in improving the performance of construction materials due to their compacting micro-structure effect and accelerating cement hydration reaction. Considering the brittle characteristic of fiber reinforced polymer (termed as FRP) tube encased concrete and inferior properties of recycled concrete, nanoparticles were used in FRP tube encased recycled aggregate concrete. The axial compressive performance of FRP tube used in recycled concrete treated with nanoparticles strengthening, termed as FRP-NPRC, were investigated by axial compression experiments and theoretical analysis. Five experimental variables were considered including (1) the dosages and (2) varieties of nanoparticles (i.e. 1% and 2% of nanoSiO2, 1% and 2% of nanoCaCO3), (3) replacement ratios of recycled coarse aggregates (termed as RCAs) (0%, 50%, 70% and 100%) the RCAs were mainly produced from the waste cracked bricks, (4) the number of glass FRP (GFRP) tube layers (2, 4 and 6-layer) and (5) the mixing methods of concrete. Results indicate that the combination of FRP confinement and nanoparticle modification in recycled concrete exhibited up to 76.2% increase in compressive strength and 7.62 times ductility improvement. Furthermore, a design-oriented stress–strain model on the basis of the ultimate condition analysis were executed to evaluate the stress–strain property of this strengthened component

Overexpression of N-Myc Downstream-Regulated Gene 2 (NDRG2) Regulates the Proliferation and Invasion of Bladder Cancer Cells In Vitro and In Vivo

N-Myc downstream-regulated gene 2 (NDRG2) is a candidate tumor suppressor gene, which plays an important role in controlling tumor growth. The aim of this study was to investigate the expression of NDRG2 gene in bladder cancer (BC) tissues and several bladder cancer cell lines, and to seek its clinical and pathological significance. Ninety-seven bladder carcinoma and 15 normal bladder tissue sections were analyzed retrospectively with immunohistochemistry. The human bladder cancer cell line T24 was infected with LEN-NDRG2 or LEN-LacZ. The effects of NDRG2 overexpression on T24 cells and T24 nude mouse xenografts were measured via cell growth curves, tumor growth curves, flow cytometric analysis, western blot and Transwell assay. NDRG2 was highly expressed in normal bladder tissue, but absent or rarely expressed in cacinomatous tissues (χ2=8.761, p < 0.01). The NDRG2 level was negatively correlated with tumor grade and pathologic stage(r=-0.248, p < 0.05), as well as increased c-myc level (r=-0.454, p< 0.001). The expression of NDRG2 was low in the three BC cell lines. T24 cells infected with LEN-NDRG2 showed inhibition of proliferation both in vitro and in vivo, and NDRG2 overexpression can inhibit tumor growth and invasion in vitro