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The gradient nanostructure is machined on the aluminum (Al) alloy by the two-dimensional ultrasonic surface burnishing process (2D-USBP). The mechanism of why the gradient nanostructure enhances wear resistance is investigated. The mechanical properties and microstructure characterization for the gradient nanostructure are performed by operating a nanoindenter, transmission electron microscopy (TEM), and electron backscattered diffraction (EBSD). Dry wear tests are performed on the samples before and after machining to evaluate the wear resistance and mechanisms. The effect of the gradient nanostructure on the wear resistance is explored by developing the crystal plasticity (CP) finite element and molecular dynamics (MD) models. The characterization results show that the 2D-USBP sample prepared a gradient structure of ∼600 µm thick on the aluminum surface, increasing the surface hardness from 1.13 to 1.71 GPa and reducing the elastic modulus from 78.84 to 70.14 GPa. The optimization of the surface microstructure and the increase of the mechanical properties effectively enhance the wear resistance of the sample, with 41.20%, 39.07%, and 54.58% of the wear scar areas for the 2D-USBP treated samples to the original samples under 5, 10, and 15 N loads, respectively. The gradient nanostructure hinders the slip of dislocations inside the sample during the wear process and reduces the size and scope of plastic deformation; meanwhile, the resistance to deformation, adhesion, and crack initiation and propagation of the sample surface is improved, resulting in enhanced wear resistance.

ABSTRACTHigh-ductility cementitious composites (HDCCs) with multiple cracking and excellent tensile strain behavior have been widely studied. The fiber component plays a pivotal role and its surface state directly determines the [...]

This paper describes a balanced frequency shift keying (FSK) modulation, namely quasi-balanced FSK (QB-FSK), for energy-efficient high-data-rate communication. Not suffering from data-pattern dependency, the proposed modulation method enables frequency modulation (FM) over 100 Mb/s by utilizing a wideband phase-locked loop (PLL). The QB-FSK signal is generated with the same baseband clock frequency as the non-return zero (NRZ)-coded binary FSK (BFSK) signal, resulting in improved bandwidth efficiency compared to other balanced FSK signals. For demodulation, the receiver employs a sideband energy detection (SB-ED) method. A FM discriminator converts the QB-FSK signal to an on-off keying (OOK) signal. After that, a band-pass filter (BPF) is used to filter out 1/f noise and dc offset. Based on the proposed QB-FSK modulation and the SB-ED method, a prototype FSK transceiver is implemented in 65-nm CMOS for high-data-rate sub-6-GHz proprietary wireless connectivity. The receiver successfully demodulates data at a rate of 200 Mb/s with a sensitivity of –67 dBm, while the transmitter can achieve a maximum data rate of 400 Mb/s. The 200-Mb/s transceiver achieves an energy efficiency of 0.14 nJ/b.

Dissimilatory iron reduction (DIR) coupled with carbon cycling is increasingly being recognized as an influential process in freshwater wetland soils and sediments. The role of DIR in organic matter (OM) mineralization, however, is still largely unknown in lake sediment environments. In this study, we clarified rates and pathways of OM mineralization in two shallow lakes with seasonal hydrological connectivity and different eutrophic situations. We found that in comparison with the domination of DIR (55%) for OM mineralization in Lake Xiaoxingkai, the contribution of methanogenesis was much higher (68%) in its connected lake (Lake Xingkai). The differences in rates and pathways of sediment OM mineralization between the two lakes were attributed to higher concentrations of carbonate associated iron oxides (Fecarb) in Lake Xiaoxingkai compared to Lake Xingkai (P = 0.002), due to better deposition mixing, more contributions of terrigenous detrital materials, and higher OM content in Lake Xiaoxingkai. Results of structural equation modeling showed that Fecarband total iron content (TFe) regulated 25% of DIR in Lake Xiaoxingkai and 76% in Lake Xingkai, accompanied by a negative effect of TFe on methanogenesis in Lake Xingkai. The relative abundance and diversity of Fe-reducing bacteria were significantly different between the two lakes, and showed a weak effect on sediment OM mineralization. Our findings emphasize the role of iron minerals and geochemical characterizations in regulating rates and pathways of OM mineralization, and deepen the understanding of carbon cycling in lake sediments.

Civil aviation noise is one of the main factors hindering the growth of the civil aviation industry. With the increase in global air traffic demand, the problem of aviation noise pollution will become more and more serious. It is of great significance to carry out research in aviation noise. First, by summarizing the characteristics of aviation noise metrics, this paper divides them into three categories: single event noise metrics, cumulative exposure metrics, and daily metrics. Representative metrics of each category are selected for explanation and in-depth analysis. Second, according to the principles of aviation noise prediction models, this paper classifies these existing models into three categories: best practice models, scientific models, and machine learning models. Relevant academic research results are summarized. The best practice model regards the aircraft as noise point source, and its specialty is to predict noise under complex air traffic conditions. The scientific model considers the noise from the level of aircraft components and reflects the underlying physical effects. Based on data, the machine learning model uses algorithms to mine the hidden relationship between various factors and noise to achieve the purpose of noise prediction. Then, this paper introduces two kinds of aviation noise simulation software based on the best practice and scientific models, and lists their access addresses. Finally, challenges and prospects are presented from three aspects: metrics, prediction models and simulation software.

BackgroundSilent MR angiography (silent MRA) is a new generation of non-contrast enhanced angiography with outstanding advantages in visualizing cerebrovascular lesions and the follow-up after endovascular treatment for intracranial aneurysms (IAs). This study aims to investigate the reliability of silent MRA-based three-dimensional (3D) geometric description and hemodynamic calculation of IAs.Methods19 patients with 23 unruptured IAs, who underwent both silent MRA and 3D rotational angiography (3DRA), were included in this study. Computational fluid dynamics simulations were performed on all patient-specific 3D reconstruction images to compare the morphology and hemodynamics of the two different imaging models for IAs.ResultsSilent MRA models had smaller maximum and perpendicular height (mm), aneurysmal surface area (mm2), and aneurysmal volume (mm3) than 3DRA (p<0.05); the differences of the above parameters between the two models were 9.0±6.2%, 7.7±7.4%, 15.9±13.0%, and 21.4±17.5%, respectively. However, correlation analysis of morphological parameters in various dimensions and model comparison showed good overall consistency in geometrical characteristics between the two models. Moderate coherence was observed between models in time-averaged wall shear stress of aneurysm and parent vessel (TAWSS, PAWSS), aneurysm velocity (AV), parent vessel velocity, and oscillatory shear index (OSI). However, strong correlations were observed among normalized aneurysm wall shear stress (NWSS), low shear area (LSA), inflow concentration index (ICI), and normalized aneurysm velocity (NAV).ConclusionBoth morphological and hemodynamic assessments of IAs for silent MRA are comparable to 3DRA. Additionally, normalized indicators such as NWSS, LSA, ICI, and NAV were better than TAWSS, AV, and OSI in silent MRA-related hemodynamic evaluation.

The rice straw biochar (RSB) was prepared from rice straw by chemical/thermal treatment, and then characterized by scanning electron microscopy, Brunauer–Emmett–Teller, Fourier transform infrared spectroscopy, and Raman spectra. RSB was used to enhance the chemical or biological decolorization of an azo dye, orange G (OG), to evaluate the redox mediator property. Results showed that RSB could significantly accelerate the chemical reduction of OG with Na2S as the electron donor. Such an accelerating effect was positively related to RSB loading, Na2S concentration, and temperature, but negatively related to pH. In the anaerobic biological decolorization of OG, the addition of RSB could enhance the decolorization rate from 53.7% to 83.5% after 48 h. The synergistic effect of RSB on the biological decolorization of OG could be attributed to the role of redox mediator of the oxygen group on the surface of RSB, which could accelerate the electrons transfer from substrate to azo bond. The functioning of RSB as a redox mediator to enhance the decolorization rate was further verified in a continuous flow up-flow anaerobic sludge blanket reactor. Finally, the decolorization products of OG were analyzed by UV-vis and gas-chromatography and mass spectrometry, and the mechanism was subsequently proposed.

Gradient nanostructure layer (GNL) is machined on 7075-aluminum by the ultrasonic-assisted surface burnishing (UASB) setup. Compared with the traditional burnishing, the advantages of UASB are discussed by the characterization of GNL. Furthermore, wear experiments with the samples machined by UASB and traditional burnishing are also performed, respectively. It introduces numerical simulation methods to investigate the varieties of grain sizes during UASB and reveal the relevant mechanism. The results exhibit that the obvious GNL forms on the sample surface after UASB, and the samples have ideal surface roughness and gradient hardness distribution. The dry wear experiments show that GNLs have good wear performances under low load, but poor wear performances under high load. Because GNL has high nanohardness, residual compressive stress and poor plasticity-toughness. These reasons result in such contradictory wear characteristics.

Burnishing experiments with different burnishing parameters were performed on a computer numerical control milling machine to characterize the surface roughness of an aluminum alloy during burnishing. The chaos theory was employed to investigate the nonlinear features of the burnishing system. The experimental results show that the power spectrum is broadband and continuous, and the Lyapunov exponent ? is positive, proving that burnishing has chaotic characteristics. The chaotic characteristic parameter, the correlation dimension D, is sensitive to the time behavior of the system and is used to establish the corresponding relationship with the surface roughness. The correlation dimension was the largest, when the surface roughness was the smallest. Furthermore, when the correlation dimension curve decreases, the roughness curve increases. The correlation dimension and surface roughness exhibit opposite variation trends. The higher the correlation dimension, the lower the surface roughness. The surface roughness of the aluminum alloy can be characterized online by calculating the correlation dimension during burnishing.

A feature parameter was proposed to quantitatively explore the boundedness of running-in attractors; its variation throughout the friction process was also investigated. The enclosing radius Rwas built with recurrence plots (RPs) and recurrence qualification analysis (RQA) by using the time delay embedding and phase space reconstruction. Additionally, the typology of RPs and the recurrence rate (RR) were investigated to verify the applicability of Rin characterizing the friction process. Results showed that Ris larger at the beginning, but exhibits a downward trend in the running-in friction process; Rbecomes smooth and trends to small steady values during the steady-state friction period, and finally shows an upward trend until failure occurs. The evolution of R, which corresponded with the typology of RPs and RR during friction process, can be used to quantitatively analyze the variation of the running-in attractors and friction state identifacation. Hence, Ris a valid parameter, and the boundedness of running-in attractors can offer a new way for monitoring the friction state of tribological pairs.

Lysosome-selective Raman probe, Lyso-BADY, was created with improved Raman signal intensity, stability as well as specificity under the visualization of hyperspectral stimulated Raman scattering (SRS) microscopy. Prolonged exposure to irradiation further proved its photostability and potentiality for continuous imaging.

To evaluate the bending performance of a steel fiber-reinforced concrete shield segment, bending testing was conducted on prism specimens and full-scale segments with 30 kg/m3 and 40 kg/m3 steel fiber. The results show that, with increasing fiber content, the ultimate and equivalent flexural strengths increase, while the flexural toughness of the prism concrete specimen increases by approximately 15%. With increasing fiber content, the flexural capacity of the shield tunnel segment increases, the peak load increases by 24%, the crack number increases, and the average crack width decreases. During bending tests, the steel fiber-reinforced concrete segment shows remarkable characteristics of strain hardening and multiple cracking. The embedded parts reduce the cross-sectional area and cause stress concentration in the mid-span; therefore, the main crack form in this region.

A novel polybenzoxazine for effective removal of Cr(VI) from aqueous solution has been fabricated by using inexpensive CuCl2–melamine complex, bisphenol A and formaldehyde. In the curing process of benzoxazine monomer, different curing media can guide the directional distribution of functional groups of different polarity in the benzoxazine monomer, and thus can achieve the effect of regulating the interfacial properties of polybenzoxazine, and achieved an amine-rich surface and a suitable surface morphology by changing the monomer structure and the ratio of raw materials. This novel polybenzoxazine sorbent was characterized by using high-resolution scanning electron microscopy, energy dispersive spectrometer, Fourier transform infrared spectroscopy and thermogravimetric analysis. The experimental maximum removal efficiency for Cr(VI) was up to 96.7% and adsorption capacity was 116.32 mg/g at solution pH of 2 with temperature of 25°C. Langmuir model was successfully fitted with various curves obtained at different temperatures, and the kinetic data were well described by pseudo-second-order model. The novel polybenzoxazine absorbent promises such advantages as high removal efficiency, low cost, facile fabrication and good recycling performance.

Friction experiments are conducted on a ring-on-disk tribometer, and friction noise produced during the friction process is extracted by a microphone. The phase trajectory and chaotic parameters of friction noise are obtained by phase-space reconstruction, and its attractor evolution is analyzed. The results indicate that the friction noise is chaotic because the largest Lyapunov exponent is positive. The phase trajectory of the friction noise follows a “convergence-stability-divergence” pattern during the friction process. The friction noise attractor begins forming in the running-in process, and the correlation dimension Dincreases gradually. In the stable process, the attractor remains steady, and Dis stable. In the last step of the process, the attractor gradually disappears, and Ddecreases. The friction noise attractor is a chaotic attractor. Knowledge of the dynamic evolution of this attractor can help identify wear state changes from the running-in process to the steady and increasing friction processes.

The therapeutic administration of recombinant proteins is utilized in a multitude of research studies for treating various diseases. In this study, we investigate the therapeutic potential of Orosomucoid 2 (Orm2), an acute phase protein predominantly secreted by hepatocytes, for treating non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). Our results show that high Orm2 expression prevents high-fat-diet (HFD)-induced obesity in mice. Pharmacological administration of recombinant ORM2 protein ameliorates hepatic steatosis, inflammation, hepatocyte injury, and fibrosis in mouse livers afflicted by NAFLD and NASH under dietary stress. Orm2 knockout mice develop spontaneous obesity under a regular diet and exacerbate HFD-induced steatosis, steatohepatitis, and fibrosis. Mechanistically, Orm2 deletion activates the Erk1/2-PPARγ-Cd36 signaling pathway, increasing fatty acid uptake and absorption in hepatocytes and mice. Overall, our findings underscore the critical role of Orm2 in preventing NASH and associated NAFLD in the context of obesity.

The development of high-performance electrocatalyst with earth-abundant elements for water-splitting is a key factor to improve its cost efficiency. Herein, a noble metal-free bifunctional electrocatalyst was synthesized by a facile pyrolysis method using sucrose, urea, Co(NO3)2and sulfur powder as raw materials. During the fabrication process, Co, S co-doped graphitic carbon nitride (g-C3N4) was first produced, and then this in-situ-formed template further induced the generation of a Co, N, S tri-doped graphene coupled with Co nanoparticles (NPs) in the following pyrolysis process. The effect of pyrolysis temperature (700, 800, and 900 °C) on the physical properties and electrochemical performances of the final product was studied. Thanks to the increased number of graphene layer encapsulated Co NPs, higher graphitization degree of carbon matrix and the existence of hierarchical macro/meso pores, the composite electrocatalyst prepared under 900 °C presented the best activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with outstanding long-term durability. This work presented a facile method for the fabrication of non-noble-metal-based carbon composite from in-situ-formed template and also demonstrated a potential bifunctional electrocatalyst for the future investigation and application.

The spinel Li4Ti5O12/rutile-TiO2@carbon (LTO-RTO@C) composites were fabricated via a hydrothermal method combined with calcination treatment employing glucose as carbon source. The carbon coating layer and the in situ formed rutile-TiO2can effectively enhance the electric conductivity and provide quick Li+diffusion pathways for Li4Ti5O12. When used as an anode material for lithium-ion batteries, the rate capability and cycling stability of LTO-RTO@C composites were improved in comparison with those of pure Li4Ti5O12or Li4Ti5O12/rutile-TiO2. Moreover, the potential of approximately 1.8 V rechargeable full lithium-ion batteries has been achieved by utilizing an LTO-RTO@C anode and a LiFePO4@N-doped carbon cathode.

In this paper, we introduce a novel model of a hydro-turbine system with the effect of surge tank based on state-space equations to study the nonlinear dynamical behaviors of the hydro-turbine system. The critical points of Hopf bifurcation and the relationship of the stability satisfying with the adjustment coefficients are obtained from direct algebraic criterion. Furthermore, the bifurcation diagrams and Lyapunov exponents are presented and analyzed. The dynamical behaviors of the points with representative characteristics are identified and studied in detail. Both theoretical analysis and numerical simulations show that chaotic oscillations, which cannot stabilize the system, may occur with the changes of adjustment coefficients. To control the undesirable chaotic behaviors in this system, fuzzy sliding mode governor based on the sliding mode control (SMC) and the fuzzy logic are designed, and considering the bounded disturbance. Finally, series of numerical simulations are presented to verify the effectiveness of the proposed governor, which prove that the hydro-turbine governing system can maintain a better operation station under the designed governor. [ABSTRACT FROM AUTHOR]

This topic mainly research the high back pressure heat supply technology of steam turbine generator unit and the correlation analysis of turbine under high back pressure operating condition. High back pressure heat supply is an energy saving technology developed in order to meet the requirements of energy saving and environmental protection. This technology can not only reduce the cold end losses to improve the thermal efficiency of power plant, but also decrease the energy loss and pollution emissions because it take the place of traditional heating boiler. High back pressure heat supply of steam turbine is to increase the quantity of air inlet and outlet as well as exhaust temperature through improving turbine back pressure. For condensing steam turbine unit of 50 MW studied in this article, back pressure of which rise to 0.032MPa from 0.0046MPa, and the exhaust temperature will increase to 70 °C respectively. Through the calculation of rated condition and variable condition, we can obtain the impact to the unit due to the change of back pressure, and for unit of 50 MW can reduce 30876.9 tons of standard coal consumption in a heating period. It can also decrease the emission of carbon dioxide, sulfur dioxide, smoke and ashes, which effect of energy saving and emission reducing is very obvious.

A series of macropore host-guest catalysts were prepared by third nanoassembly technique. nanoassembly support had a pore volume of 1.32cm3 /g,a specific surface area of 220m2/g, average pore diameter of 27.3nm, the most probable pore diameter of 40nm, a low stacking density of 0.34g/cm3. The results of the XRD and TEM showed that the part of pore was blocked with increasing the amount of active metal. But the aggregation phenomenon was improved by adding uniformly co-impregnant, and the amount of active metal was up to 40%. The lamellar structure of sulfided state metal was formed which the length were between 8 nm to 10 nm and layer were 3~9. Hydrogenation performance of the different catalysts has been evaluated. The removal rates of desulfurization, denitrification, residual carbon and demetalization for hydrotreating in one gram active metal per 100mL volume for FB30 were as 2.0, 2.6, 2.0 and 2.5 times as FC, respectively. The results explained that the macropore host-guest catalyst had higher activity for hydrotreating residue.

A novel sulfur/polyacrylonitrile/graphene nanocomposite has been synthesized via a simple combination of ballmilling with low temperature heat-treatment. The nanocomposite was examined as a cathode for high performance lithium/sulfur batteries. The SEM and TEM observations revealed that sulfur/polyacrylonitrile particles are incorporated into graphene networks homogenously. Charge/discharge tests and ac impedance spectroscopy have shown improved conductivity and electrochemical properties of the composite with the addition of graphene. The lithium cell with this ternary composite cathode delivered a discharge capacity of 612 mAh g[?]1 in the second cycle at 0.1 C, and retained about 77% of this value over 100 cycles. Even up to 4 C rate, the lithium cell demonstrated an excellent rate capability, delivering a highly reversible discharge capacity of 360 mAh g[?]1.

Calix[4]-crown-5-sulfonyl cyclothiourea derivatives 6 and 7 were synthesized from calix[4]-crown-5-monosulfonylethylenediamine derivatives 4 and 5 and carbon disulfide through nucleophilic addition and subsequent cyclization of intramolecule at room temperature in aqueous solution. The advantages of the novel protocol are the mild reaction condition, free organic solvent, simple final treatment, easy isolation of products and excellent yields.

Background It has been previously reported in several studies that deformation of parent artery (DPA) occurs after stent-assisted coil embolization (SACE) for intracranial aneurysms (IAs).Objective To investigate the predisposing factors of stent-induced DPA, as well as its effect on the follow-up of aneurysm embolization.Methods Clinical and imaging data were collected from 198 patients (201 aneurysms). Angles of the stent-covered parental artery were measured before treatment and during follow-up. Cases in which the angle had changed more than 5 degrees, were defined as DPA. The related factors of DPA were analyzed. The relation between DPA and follow-up results was also studied.Results Univariate analysis revealed that sex (p = 0.014), age (p = 0.017), aneurysm location (p < 0.001), stent type (p < 0.001), aneurysm size (p = 0.019), and pretreatment angle (p = 0.002) correlated with DPA. On the other hand, multivariate analysis revealed that aneurysms located in the anterior communicating artery (ACOA) (OR = 4.559, p = 0.013) and middle cerebral artery (MCA) (OR = 9.474, p < 0.001) were independent predisposing factors for DPA after stent implantation, whereas a braided stent (OR = 0.221, p = 0.030), flow diverter (FD) device (OR = 0.100, p = 0.028) were negative factors to develop DPA. The complete occlusion rate in the DPA group was higher (p = 0.035) than in the non-DPA group.Conclusions Aneurysms located in ACOA and MCA are more prone to DPA after SACE than aneurysms at other locations in the anterior circulation, braided stents and FD devices do not predispose to induce vascular deformation. DPA may be beneficial for the long-term cure of IAs after SACE.

Forage yield is the fundamental ecosystem service of grasslands. While the quantitative responses of forage yield to nitrogen (N) enrichment are well known, its qualitative responses remain unclear. Even less known is the relative contribution of changes in community composition to the quality of the yield at the community level. We examined the quantitative and qualitative responses of forage yield at both plant functional group and community levels with factorial treatments of N addition and mowing in a temperate steppe. Nitrogen addition significantly enhanced the community-level yield by favoring the growth of rhizomatous grass. Mowing tended to mediate the impacts of N addition on the yield. Nitrogen addition increased the concentrations of crude protein and crude fat in forage at the community level. Neither the main effects of mowing nor its interactive effects with N addition affected forage quality. The N-induced shifts in plant species composition significantly contributed to the effects of N addition on forage quality at the community level. Our results suggest that mowing wound weaken the positive effects of N deposition on the quantity but not the quality of forage yield. Changes in plant community composition are important in driving the qualitative responses of yield to N deposition.

Background: Forage production is the fundamental ecosystem service of grasslands. Although forage consumption occurs at community level, most studies focused on species-level changes of forage quality. The quantitative and qualitative changes of forage production are driven by species-specific trait, intra-specific plasticity, and species turnover. We examined the changes in forage production and digestibility after 5-year factorial treatments of nitrogen (N) addition and mowing in a temperate steppe and linked such changes to community assembly under the Price equation framework. Results: Nitrogen addition significantly reduced species richness, increased forage production, but did not change forage digestibility (indicated by the total Ca+Mg concentrations). Mowing did not affect forage production and digestibility. The positive effects of N addition on forage production were driven by the enhancement of abundance of the remaining species following N enrichment, rather than by species loss or species gain. The species identity effects could offset the effects of species richness loss or gain on forage production and digestibility. Conclusions: Our results highlight the importance of a community perspective in addressing the quantitative and qualitative changes of forage production under global change pressure of N enrichment. Species identity is important in determining the contribution of different processes of community assembly to ecosystem services.

A novel two-dimensional ultrasonic surface burnishing process (2D-USBP) is proposed. 7075-T6 aluminum samples are processed by a custom-designed 2D-USBP setup. Parameter optimization of 2D-USBP is conducted to determine the best processing strategy of 7075-T6 aluminum. A uniform design method is utilized to optimize the 2D-USBP process. U13(133) and U7(72) tables are established to conduct parameter optimization. Burnishing depth, spindle speed, and feed rate are taken as the control parameters. The surface roughness and Vickers hardness are taken as the evaluation indicators. It establishes the active control models for surface quality. Dry wear tests are conducted to compare the wear-resistance of the 2D-USBP treated sample and the original sample. Results show that the machining quality of 2D-USBP is best under 0.24 mm burnishing depth, 5000 r/min spindle speed, and 25 mm/min feed rate. The surface roughness Saof the sample is reduced from 2517.758 to 50.878 nm, and the hardness of the sample surface is improved from 167 to 252 HV. Under the lower load, the wear mechanism of the 2D-USBP treated sample is mainly abrasive wear accompanied by delamination wear, while the wear mechanism of the original sample is mainly delamination wear. Under the higher load, the accumulation of frictional heat on the sample surface transforms the wear mechanisms of the original and the 2D-USBP treated samples into thermal wear.

To investigate the influence of surface roughnesses on the dynamic characteristics of AISI 5120 steel in sliding friction process, a suite of running-in experiments are performed on a pin-on-disk tribometer. The running-in attractor is used to analyze the high-dimensional features of a friction system under different surface roughnesses. The experimental results show that the roughnesses of different original surfaces evolve to the same value in stable wear stage. The pin-on-disk friction system has a chaotic nature and exists a running-in attractor. The original surface of a disk of Ra = 0.953 μm is the most conducive to shorten the running-in duration, reduce the friction coefficient value, and improve the stability of the friction system. This roughness value is termed as the optimum surface roughness. It is an ideal working surface for the friction pair in the running-in design.

This study evaluates the effect of sulphoaluminate cement content on the performance of high ductility cementitious composite (HDCC) as repair material. To prepare the HDCC, Portland cement was partially replaced with 10%, 15%, or 20% rapid hardening sulphoaluminate cement. The compressive and flexural strength developments and tensile properties of the sulphoaluminate cement containing HDCC were investigated. The microscopic mechanism by which sulphoaluminate cement affects the macroscopic performance of HDCC was examined by scanning electron microscopy. Before 14 d, the mechanical properties were directly proportional to the sulphoaluminate cement content, but at 28 d, the sulphoaluminate cement content exerted no obvious effect. The sulphoaluminate cement content largely influenced the ultimate tensile strain but little affected the tensile strength. The mechanical properties were optimized in HDCC containing 10% and 15% sulphoaluminate cement. The reduced tensile ductility in sulphoaluminate cement containing HDCC is attributed to the large amount of ettringite formed on the surfaces of the reinforcing PVA (polyvinyl alcohol) fibers.

To develop high ductility cementitious composites (HDCC) for repairing hydraulic discharge structures, the effect of water-binder ratio, polyvinyl alcohol (PVA) fiber content, and fly ash content on the tensile properties of HDCC was studied. The results show that with increase in water-binder ratio and/or fly ash content, the ultimate tensile strain of HDCC increases gradually, while the ultimate tensile stress and the initial cracking stress decrease. With different fiber contents, the tensile stress-strain curves of HDCC coincide in the linear elastic stage, and the initial cracking stresses are roughly the same; with increase in fiber content, the ultimate tensile strain and ultimate tensile strength increase gradually. Based on these results, the appropriate mix proportions for the HDCC material were determined for repairing hydraulic discharge structures.

In this paper, the creep rupture strength for Super304H weld joints was evaluated by isothermal method. Service life prediction curves indicate that Super304H weld joints could guarante safety service for 105 hours at 625degC, which is in according with the Ultra-supercritical units steam conditions. When the stress is higher, the rupture mode of creep specimens was transcrystalline fracture, and results in forming dimples. When the stress is lower, the rupture mode of creep specimens was creep rupture, and results in cleavage rupture. So under the effect of long term low stress, creep cavities joined each other along the grain boundary.

To describe the dynamic evolutionary law and tribological behavior of the tribopair AISI 52100-AISI 1045, rotational experiments were conducted by sliding a disk against a static pin. The multidimensional phase spaces were reconstructed based on the scalar time-series by the time-delay embedding technique, and the multivariate graph-based method was used to visualize the overall picture of the phase space. The evolution of radar plots and the corresponding multivariate graph centrobaric trajectory (MGCT) is consistent with the description of “running-in, steady-state and increasing friction stages,” and can serve as effective indicators for the friction state transitions. Results show that the radar plot can inform quantitative interpretations of friction process identification. Therefore, the multivariate graph-based method is a useful approach to characterize the nonlinear dynamics of tribological behaviors.

To explore the recursive characteristics of a running-in attractor, recurrence plot (RP) and recursive parameters are used to investigate the dynamic features of the structure. The running-in attractor is constructed based on friction noise signals generated from the ring-on-disk wear experiments. The RPs of the running-in attractor are then reproduced in a two-dimensional space. Recursive parameters, recurrence rate (RR), entropy (ENTR), and trend of recurrence (RT) are calculated. Results show that the RP evolves from a disrupted pattern to a homogeneous pattern and then returns to a disrupted pattern in the entire wear process, corresponding to the “formation–stabilization–disappearance” stage of the running-in attractor. The RR and ENTR of the running-in attractor sharply increase at first, remain steady, and then sharply decrease. Moreover, the inclination of RT in the normal wear process is smaller than those in the other two processes. This observation reveals that the running-in attractor exhibits high stability and complexity. This finding may contribute to the running-in state identification, process prediction, and control.

Computing the shortest-path distances between nodes is a key problem in analyzing social graphs. Traditional methods like breadth-first search (BFS) do not scale well with graph size. Recently, a Graph Coordinate System, called Orion, has been proposed to estimate shortest-path distances in a scalable way. Orion uses a landmark-based approach, which does not take account of the shortest-path distances between non-landmark nodes in coordinate calculation. Such biased input for the coordinate system cannot characterize the graph structure well. In this paper, we propose Pomelo, which calculates the graph coordinates in a decentralized manner. Every node in Pomelo computes its shortest-path distances to both nearby neighbors and some random distant neighbors. By introducing the novel partial BFS, the computational overhead of Pomelo is tunable. Our experimental results from different representative social graphs show that Pomelo greatly outperforms Orion in estimation accuracy while maintaining the same computational overhead.

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Acute lymphoblastic leukemia (ALL) in children is a paradigm of disseminated cancer that is curable with chemotherapy, yet current treatment fails to cure about 20% of patients, for reasons that remain unknown. In a genome-wide assessment of in vivo treatment-induced changes in gene expression in ALL cells using the Affymetrix U95A and U133A oligonucleotide microarray, we found that patients who eventually relapsed did not up-regulate expression of the pro-apoptotic beta-2 adrenergic receptor gene (ADRB2) in their ALL cells after initial treatment with methotrexate and mercaptopurine. After treatment we observed a 5-fold lower level of ADRB2 gene expression in leukemia cells of patients who ultimately relapsed. We found a common genetic polymorphism in the ADRB2 promoter that was significantly linked to high-dose methotrexate induced up-regulation in ADRB2 gene expression in ALL cells. Moreover, the ADRB2 promoter haplotype was significantly linked to poor early treatment response in ALL cells from 242 children (i.e., probability of event-free survival at two years, p=0.0275 stratified by risk groups). These findings have revealed a germline polymorphism that is linked to the early antileukemic effects of ALL chemotherapy and provide new insights into genetic determinants of ALL treatment efficacy.