Demystifying the Performance of HPC Scientific Applications on NVM-based Memory Systems

The emergence of high-density byte-addressable non-volatile memory (NVM) is promising to accelerate data- and compute-intensive applications. Current NVM technologies have lower performance than DRAM and, thus, are often paired with DRAM in a heterogeneous main memory. Recently, byte-addressable NVM hardware becomes available. This work provides a timely evaluation of representative HPC applications from the "Seven Dwarfs" on NVM-based main memory. Our results quantify the effectiveness of DRAM-cached-NVM for accelerating HPC applications and enabling large problems beyond the DRAM capacity. On uncached-NVM, HPC applications exhibit three tiers of performance sensitivity, i.e., insensitive, scaled, and bottlenecked. We identify write throttling and concurrency control as the priorities in optimizing applications. We highlight that concurrency change may have a diverging effect on read and write accesses in applications. Based on these findings, we explore two optimization approaches. First, we provide a prediction model that uses datasets from a small set of configurations to estimate performance at various concurrency and data sizes to avoid exhaustive search in the configuration space. Second, we demonstrate that write-aware data placement on uncached-NVM could achieve $2$x performance improvement with a 60% reduction in DRAM usage.Comment: 34th IEEE International Parallel and Distributed Processing Symposium (IPDPS2020

1-(4-Cyano­benz­yl)-3,5-dimethyl­pyridinium bis­(benzene-1,2-dithiol­ato)nickelate(III)

The asymmetric unit of the title compound, (C15H15N2)[Ni(C6H4S2)2], contains half each of two independent centrosymmetric anions and a single cation in a general position. The NiIII ions are coordinated by four S atoms in a square-planar geometry. The anions exhibit two packing modes, viz. stacked along the a axis in a face-to-face fashion with an alternate arrangement of anions and cations, and stacked in a side-by-side fashion, forming ribbons parallel to (011)

Research on Suppressing Premixed Fuel-air Explosion by Ultra-fine Cold Aerosol

AbstractThe problem of prevention and suppression of gas-and air explosions is extremely important because such explosions represent serious threat to firemen life. It is significant that ultra-fine cold aerosol with typical characteristics of compressibility, flow ability and good dispersion attributed, can suppress the deflagration and detonation of leaking of flammable oil gases. In this paper, some series of the explosion suppression experiments were carried out in the laboratory 20-liter apparatus with three gas routes and two igniters of chemical and high-voltage pulse which provide a reliable, multiple-point ignition source. The main series were about the suppressing the developed explosion process of oil gas premixed air and ultra-fine cold aerosol, or 1301 fire extinguishing agent. The results are shown that in case of suppressing the developed explosion, the increase of the concentration of ultra-fine powder and 1301 both causes the decrease of the maximum explosion pressure and maximum rate of pressure rise of oil gases. Moreover, 1301 fire extinguishing agent has distinctly threshold nature and the induced time of oil explosion is delayed. Furthermore, it is shown that the explosion suppression effect is associated to inherent property and concentration of suppressing agent and ignition condition. And the rank of suppressing capability of ultra-fine aerosol or gas suppressing agent for oil gas atmosphere was proposed, and the maximum suppressed explosion pressure may be used as the criterion to estimate explosion-suppression efficiency of oil gas. This research helps optimize explosion suppression condition of oil gas, and have important reference values for further application on explosion suppression technology in large oil rank farm and other danger sites

A hydraulic fault diagnosis method based on sliding-window spectrum feature and deep belief network

The vibration signal of hydraulic system contains abundant state information, so vibration testing technology is an effective way to realize the fault diagnosis of hydraulic system. However, the mapping relation between signal characteristic and system state is complex and the expression meaning of characteristic is obscure, which brings a great challenge to the hydraulic fault diagnosis. The DBN, a newly proposed deep learning model, has an advantage of autonomously learning and reasoning. And it is good at studying the concealed representation of data and highlighting the feature expression. So, it is contributive to deal with the problems of large capacity data like high dimension, redundancy, and nonlinear etc. Therefore, DBN is chosen as the fault diagnosis method in this paper. Meanwhile, given that the difficulty in feature extraction of hydraulic vibration signal and the important influence of input feature vector to the diagnosing of DBN, a fast and effectively feature extraction method based on sliding-window spectrum feature (SWSF) is proposed. It is effective in remaining the integrity of feature, avoiding the risking of relative shifting of characteristic spectrum, and decreasing the dimensions of feature vector. The experimental results demonstrate that the combination of SWSF and DBN is a fast and effective approach to realize the fault diagnosis of hydraulic system

Study on properties of Al film on CFRP after cryogenic-thermal cycling

AbstractAl film on CFRP has been tested by cryogenic-thermal cycling according to the especial condition of space. Properties of aluminum film have been characterized by electron pull apparatus, XRD and SEM. The result shows that the adhesion of Al film increases slowly at early stage of cryogenic-thermal cycling. When the times of cryogenic-thermal cycling exceed 50, the adhesion of Al film becomes stability, and then the adhesion of Al film decrease slowly when cycling times from 100 to 600. After 600 times, the adhesion of Al film becomes stability again. The microcrack appears on the surface of Al film after 50 times, and the amounts of microcrack increase and microcrack is coarsening versus times of cryogenic-thermal cycling. The structure of Al film is changing slowly during cryogenic-thermal cycling

Effects of aminoguanidine on retinal apoptosis in mice with oxygen-induced retinopathy

<b>AIM:</b> To explore the protective effects of aminoguanidine (AG) on retinal apoptosis in mice with oxygen-induced retinopathy (OIR).<b>METHODS</b>:A total of 80 C57BL/6J mice, aged 7 days, were randomly divided into four groups:normal, high oxygen, high oxygen saline and high oxygen treated with AG. In the normal group, mice were housed in normoxic conditions from postnatal day P7 to P17. Mice in the other 3 groups were placed under hyperoxic conditions (75±2%O2) in an oxygen-regulated chamber for 5 days and subsequently placed in normoxic conditions for 5 days. Mice in the AG group were treated once daily, from P12 to P17, with AG hemisulfate (100mg/kg body weight, intraperitoneally) dissolved in physiological saline. An equivalent amount of 0.9% physiological saline was administered, as above, to mice in the high oxygen saline group. Ten mice were randomly selected from each group on P14 and on P17, euthanized and the retinas examined. Apoptotic cells in the retina were detected using the terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) method. The expression of nitric oxide synthase (iNOS) in the retina was detected by immunohistochemistry and changes in rod cells were observed using electron microscopy.<b>RESULTS</b>:TUNEL-positive cells and iNOS immunoreactive neurons were present in the inner nuclear and ganglion cell retinal layers of mice in the high oxygen group. The number of TUNEL-positive cells was significantly greater in the high oxygen group compared with the normal group (<i>t</i>=-20.81, <i>P</i>14d <0.05; <i>t</i>=-15.05, <i>P</i>17d<0.05). However, the number of TUNEL-positive cells in the AG treatment group was significantly lower (<i>t</i>=-13.21, <i>P</i>14d<0.05; <i>t</i>=-6.61,<i>P</i>17d <0.05) compared with the high oxygen group. The expression of iNOS was significantly higher in the high oxygen group compared with the normal group (<i>t</i>=-21.95, <i>P</i>14d<0.05; <i>t</i>=-17.30, <i>P</i>17d<0.05). However, the expression of iNOS in the AG treatment group was significantly lower (<i>t</i>=-12.17,<i>P</i>14d<0.05; <i>t</i>=-10.30,<i>P</i>17d<0.05) compared with the high oxygen group. The outer segments of the rods were disorganized and short in the high oxygen group. Rod morphology appeared to be slightly improved in the AG group.<b>CONCLUSION</b>:AG may protect retinal neurons in OIR by inhibiting apoptosis. The mechanism may be related to iNOS