48 research outputs found
Effects of sodium ions on synthesized alkali silica reaction gels
The alkali-silica reaction (ASR), leading to serious structural degradation, is the chemical reaction between reactive silica presenting in aggregates and hydroxyl ions from cement paste or pore solution. Although the chemical mechanism of ASR attack has been well studied for years, the mechanism of micro scale ASR gel formation leading to macro scale expansion is still under debate.
The present study aims to illustrate the performance of ASR gel by investigating the interaction between ASR gel and sodium ion from solution. In this study, ASR gels with different calcium silica (Ca/Si) ratios (0.1, 0.5, 1) are synthesized by mixing reagent Ca(OH)2 with silica fume in a sodium hydroxide solution for seven days. Afterwards, the synthesized ASR gel is immersed in sodium hydroxide solutions with different concentrations (0.1mol/L, 0.5mol/L, 1.0mol/L) for seven days. Chemical composition, structure and water content of the ASR gel before and after alkali exposure are studied by XRD, XRF and TGA.
The results confirm that an ASR gel with a targeted Ca/Si ratio can be synthesized. In addition, XRD and TGA results show that part of the calcium in the ASR gel is exchanged by sodium, leading to a structural modification. In general, this study will give further comprehension of ASR gel performance under alkaline environment, and provide detailed data to investigate the interaction between ASR gel and calcium ions in an alkaline solution in the future
Studies on the evolution of alkali silicate in a simulated alkali-silica reaction system
In this study, the interaction between the reactive silica present in aggregates and the alkalis and
hydroxyls present in the pore solution of cement paste is simulated in a chemical model system and
investigated experimentally. Various properties of the solid and liquid phases are investigated. The
results show that the nano and micro structure and properties of the formed alkali silicate change
significantly during this process
Pola Pemanfaatan Lahan dan Faktor-faktor Perkembangan Wilayah Perkotaan di Kabupaten Sleman dan Kabupaten Bantul
Penelitian ini bertujuan untuk menganalisis pertumbuhan wilayah perkotaan, terutama dinamika wilayah periurban yang menjadi target perluasan aktivitas perkotaan, terutama permukiman. Fenomena urbanisasi kontemporer ini terjadi akibat migrasi kelompok ekonomi menengah ke pinggiran kota seiring dengan meningkatnya kepadatan pusat kota yang berdampak pada penurunan kualitas lingkungan hidup. Keinginan untuk mencari lingkungan permukiman yang lebih baik merupakan faktor pendorong utama, di samping keterbatasan lahan permukiman di pusat kota. Hasil yang didapat menunjukkan bahwa perambahan lahan di wilayah periurban telah merubah struktur ruang dan pola pemanfaatan lahan. Pada dimensi ekonomi, perkembangan aktivitas perkotaan di wilayah periurban telah memicu pergeseran struktur ekonomi primer yang berbasis potensi agraris menuju sektor jasa dan perdagangan akibat perubahan struktur sosial
Faster NTRU-based Bootstrapping in less than 4 ms
Bootstrapping is a critical technique in constructing fully homomorphic encryption (FHE), which serves to refresh the noise in FHE ciphertexts, enabling an arbitrary number of homomorphic operations. Among published results, the TFHE-rs library [Zam22] offers the fastest bootstrapping implementation on CPU platforms by taking advantage of AVX-512 instructions.
In this paper, we improve the efficiency of the bootstrapping algorithm based on the NTRU problem. First, we introduce the approximate gadget decomposition method tailored for NTRU ciphertext, reducing the number of NTT operations required for external products. Second, by integrating the approximate decomposition and key unrolling techniques, we improve the performance of CMux-based blind rotation. Third, for the automorphism-based blind rotation method, we present a hybrid window size technique that reduces the number of automorphisms by 34% compared to recent work [XZD+23](in Crypto23).
Subsequently, we implement the proposed bootstrapping algorithm on the CPU platform with AVX instructions. Experimental results demonstrate that our method only takes 3.8ms, which achieves a 1.8× speedup compared to the TFHE-rs library. Finally, we propose an efficient FPGA accelerator based on the CMux method, which not only achieves the best performance but also exhibits high throughput advantages. Our accelerator can improve performance by 2x compared to state-of-the-art FPGA implementations (e.g., FPT)
A Review of Spatter in Laser Powder Bed Fusion Additive Manufacturing: In Situ Detection, Generation, Effects, and Countermeasures
Spatter is an inherent, unpreventable, and undesired phenomenon in laser powder bed fusion (L-PBF) additive manufacturing. Spatter behavior has an intrinsic correlation with the forming quality in L-PBF because it leads to metallurgical defects and the degradation of mechanical properties. This impact becomes more severe in the fabrication of large-sized parts during the multi-laser L-PBF process. Therefore, investigations of spatter generation and countermeasures have become more urgent. Although much research has provided insights into the melt pool, microstructure, and mechanical property, reviews of spatter in L-PBF are still limited. This work reviews the literature on the in situ detection, generation, effects, and countermeasures of spatter in L-PBF. It is expected to pave the way towards a novel generation of highly efficient and intelligent L-PBF systems
Overexpression of Polo-like kinase1 (PLK1) in chondrosarcoma and its implications for cancer progression
Polo-like kinase1 (PLK1) is a new therapeutic target for osteosarcoma with good application prospects. Whether PLK1 is highly expressed in chondrosarcoma and whether PLK1 can be a potential therapeutic target for chondrosarcoma are worth exploring. However, PLK1 expression in chondrosarcoma is scarcely investigated. Therefore, we collected 11 cases of chondrosarcoma and 26 cases of osteochondroma with complete clinical pathological data and used immunohistochemical staining to detect the expression of PLK1 in chondrosarcoma and osteochondroma and then studied its significance and relationship with clinical pathological parameters. Our results showed that the positive expression rate of PLK1 in chondrosarcoma tissue (90.91%, 10/11) was significantly higher than the rate of osteochondroma tissues (53.85%, 14/26) (
Evaluation of individual and ensemble probabilistic forecasts of COVID-19 mortality in the United States
Short-term probabilistic forecasts of the trajectory of the COVID-19 pandemic in the United States have served as a visible and important communication channel between the scientific modeling community and both the general public and decision-makers. Forecasting models provide specific, quantitative, and evaluable predictions that inform short-term decisions such as healthcare staffing needs, school closures, and allocation of medical supplies. Starting in April 2020, the US COVID-19 Forecast Hub (https://covid19forecasthub.org/) collected, disseminated, and synthesized tens of millions of specific predictions from more than 90 different academic, industry, and independent research groups. A multimodel ensemble forecast that combined predictions from dozens of groups every week provided the most consistently accurate probabilistic forecasts of incident deaths due to COVID-19 at the state and national level from April 2020 through October 2021. The performance of 27 individual models that submitted complete forecasts of COVID-19 deaths consistently throughout this year showed high variability in forecast skill across time, geospatial units, and forecast horizons. Two-thirds of the models evaluated showed better accuracy than a naïve baseline model. Forecast accuracy degraded as models made predictions further into the future, with probabilistic error at a 20-wk horizon three to five times larger than when predicting at a 1-wk horizon. This project underscores the role that collaboration and active coordination between governmental public-health agencies, academic modeling teams, and industry partners can play in developing modern modeling capabilities to support local, state, and federal response to outbreaks