Corrosion Performance of Embedded Steel Bar in Cl--contaminated Limestone Calcined Clay Cement (LC3) at initial stage of hydration

Limestone Calcined Clay Cement (LC3) presents brilliant properties in binding Cl- so that the embedded steel bars are probably protected in Cl--contaminated condition, which meets the need of sea sand application. However, the corrosion performance of steel bars embedded in LC3 paste with Cl‑ is unclear, especially in early age hydration. Thus, a series of experiments were carried out to evaluate the corrosion performance of steel bars on initial and hardened stages of hydration, including concentration of OH- and Cl- in real pore solution, open circuit potential (OCP) and chemical elements of steel bars. In terms of early age hydration, the OCP of steel bars and ions concentration in pore solution indicated that both specimens embedded in PC and LC3 pastes were at a highly corrosion state, however, elemental results showed that no obvious corrosion happened at this stage. With respect to hardened age hydration, visual corrosion could be seen on PC-embedded steel bars, with more Fe3+ and O2-, in comparison with LC3-embedded one, which was related to the much lower absolute OCP and Cl- concentration in pore solution. Overall, LC3 cement demonstrates protective effect on steel bar in special contaminated-Cl- concentration

Passivation behaviour of aluminium alloys in limestone calcined clay cement (LC³)

Limestone calcined clay cement (LC3) has emerged as a promising alternative to traditional Portland cement (PC), offering reduced carbon dioxide emissions and improved mechanical and durability-related properties. However, concerns persist regarding the durability of reinforced LC3 concrete, particularly its lower critical chloride threshold and carbonation resistance. To address this issue, aluminium alloys were suggested to be used as an alternative reinforcement. This study investigates the passivation behaviour of aluminium alloys in LC3 and compares it with that in PC. Electrochemical measurements indicate that LC3 paste exhibits higher resistance and forms a more compact film compared to PC paste, suggesting its more protective property. XRD, Raman spectroscopy, and SEM analysis provide insights into the chemical composition and thickness of the films formed on the surfaces of aluminium alloys. This study enhances our understanding of the passivation mechanisms of aluminium alloys in LC3, facilitating their potential application in LC3-based structures.</p

EMBA: Efficient memory bandwidth allocation to improve performance on intel commodity processor

On multi-core processors, contention on shared resources such as the last level cache (LLC) and memory bandwidth may cause serious performance degradation, which makes efficient resource allocation a critical issue in data centers. Intel recently introduces Memory Bandwidth Allocation (MBA) technology on its Xeon scalable processors, which makes it possible to allocate memory bandwidth in a real system. However, how to make the most of MBA to improve system performance remains an open question. In this work, (1) we formulate a quantitative relationship between a program\u27s performance and its LLC occupancy and memory request rate on commodity processors. (2) Guided by the performance formula, we propose a heuristic bound-aware throttling algorithm to improve system performance and (3) we further develop a hierarchical clustering method to improve the algorithm\u27s efficiency. (4) We implement these algorithms in EMBA, a low-overhead dynamic memory bandwidth scheduling system to improve performance on Intel commodity processors. The results show that, when multiple programs run simultaneously on a multi-core processor whose memory bandwidth is saturated, the programs with high memory bandwidth demand usually use bandwidth inefficiently compared with programs with medium memory bandwidth demand from the perspective of CPU performance. By slightly throttling the former\u27s bandwidth, we can significantly improve the performance of the latter. On average, we improve system performance by 36.9% at the expense of 8.6% bandwidth utilization rate

DCAPS: dynamic cache allocation with partial sharing

In a multicore system, effective management of shared last level cache (LLC), such as hardware/software cache partitioning, has attracted significant research attention. Some eminent progress is that Intel introduced Cache Allocation Technology (CAT) to its commodity processors recently. CAT implements way partitioning and provides software interface to control cache allocation. Unfortunately, CAT can only allocate at way level, which does not scale well for a large thread or program count to serve their various performance goals effectively. This paper proposes Dynamic Cache Allocation with Partial Sharing (DCAPS), a framework that dynamically monitors and predicts a multi-programmed workload\u27s cache demand, and reallocates LLC given a performance target. Further, DCAPS explores partial sharing of a cache partition among programs and thus practically achieves cache allocation at a finer granularity. DCAPS consists of three parts: (1) Online Practical Miss Rate Curve (OPMRC), a low-overhead software technique to predict online miss rate curves (MRCs) of individual programs of a workload; (2) a prediction model that estimates the LLC occupancy of each individual program under any CAT allocation scheme; (3) a simulated annealing algorithm that searches for a near-optimal CAT scheme given a specific performance goal. Our experimental results show that DCAPS is able to optimize for a wide range of performance targets and can scale to a large core count

Low Cost Three-Dimensional Programmed Mini-Pump Used in PCR

Programmed mini-pumps play a significant role in various fields, such as chemistry, biology, and medicine, to transport a measured volume of liquid, especially in the current detection of COVID-19 with PCR. In view of the cost of the current automatic pipetting pump being higher, which is difficult to use in a regular lab, this paper designed and assembled a three-dimensional programmed mini-pump with the common parts and components, such as PLC controller, motor, microinjector, etc. With the weighting calibration before and after pipetting operation, the error of the pipette in 10 μL (0.2%), 2 μL (1.8%), and 1 μL (5.6%) can be obtained. Besides, the contrast test between three-dimensional programmed mini-pump and manual pipette was conducted with the ORF1ab and pGEM-3Zf (+) genes in qPCR. The results proved that the custom-made three-dimensional programmed mini-pump has a stronger reproducibility compared with manual pipette (ORF1ab: 24.06 ± 0.33 vs. 23.50 ± 0.58, p = 0.1014; pGEM-3Zf (+): 11.83.06 ± 0.24 vs. 11.50 ± 0.34, p = 0.8779). These results can lay the foundation for the functional, fast, and low-cost programmed mini-pump in PCR or other applications for trace measurements