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Bugholes, considered an aesthetic problem, generally appear on concrete surfaces. Such surface imperfections may accelerate the ingression of liquids and chlorides. Chloride penetration is of crucial concern for reinforced concrete in a saline environment. Various surface penetrants have been widely used to protect concrete from environmental corrosion. However, most previous research on penetrants was conducted on concrete with minimal surface imperfections, such as bugholes or cracks. These surface blemishes bring worries about the protective effect of surface penetrants for concrete that may degrade. Surface finishing before coating increases construction costs and duration. This study focuses on the impact of surface bugholes on chloride penetration of concrete coated with surface penetrants. The surfaces of specimens have various sizes of bugholes. Specimens were immersed in a sodium chloride solution of 3% for 100 days. The test results show that silane-based penetrants have an excellent water-repellent effect even on a concrete surface with bugholes. The chloride penetration depth increased with increasing surface bughole size when the concrete surface was uncoated or coated with a low-water-repellent surface penetrant. For concrete surface treated with high-water-repellent surface penetrants, the influence of surface bugholes on chloride penetration was negligible.

Bugholes are usually considered an aesthetic problem rather than a durability problem. Surface bugholes often appear on the sidewalls of a tunnel's lining concrete, which can be mitigated but never eliminated. However, the impact of surface bugholes on concrete durability is still unidentified. In cold regions, the lining concrete of a road tunnel is exposed to de-icer solutions splashed by traffic, and it is additionally exposed to freeze–thaw (F–T) cycles. This study focuses on the durability to F–T cycles of tunnel lining concrete with surface bugholes. For the objectives, the study was carried out on a laboratory-scale F–T test using large concrete blocks. An image analysis based on the RGB values of each pixel in the coloured photographic image was performed to detect and quantify deterioration of the concrete surface throughout the F–T cycles. Although severe scaling never occurred during the 300 F–T cycles, the concrete with bugholes indicated a significant local scaling at the edges of the bugholes. Some bugholes enlarged and some merged with existing bugholes, in accordance with such local scaling. The paper presents synergetic and negative effects of bugholes on the local scaling of tunnel lining concrete exposed to F–T cycles.

Neonatal brachial plexus injury (NBPI) causes disabling and incurable muscle contractures that are driven by impaired growth of denervated muscles. A rare form of NBPI, which maintains afferent muscle innervation despite motor denervation, does not cause contractures. As afferent innervation regulates various aspects of skeletal muscle homeostasis through NRG/ErbB signaling, our current study investigated the role of this pathway in modulating contracture development. Through pharmacologic modification with an ErbB antagonist and NRG1 isoforms, we discovered that NRG/ErbB signaling does not modulate the development of contractures in neonatal mice. Instead, ErbB inhibition impeded growth in nondenervated skeletal muscles, whereas increased ErbB activation exacerbated denervation-induced skeletal muscle atrophy. This potential regulatory effect of NRG/ErbB signaling on neonatal muscle growth warrants deeper investigation.

It is known that the blazar jet emissions are dominated by non-thermal radiation while the accretion disk jets are normally dominated by thermal emission. In this work, our aim is to study the connection between the two types of emission by investigating the correlation between the blazar emission line intensity property, which embodies the nature of accretion disk, and the $\gamma$-ray flux property, which is the representative of jet emission. We compiled a sample of 656 blazars with available emission line equivalent widths ($EW$), the GeV $\gamma$-ray flux, and the SED information from the literature. In this work, we found 55 previous BCUs are now identified as FSRQs, and found 52 Changing-look blazars based on their $EW$ and 45 of them are newly confirmed. These Changing-look blazars have a larger accretion ratio (${\dot M}/{\dot M}_{\rm Edd}$) than BL Lac objects. In addition, we suggest that the lower synchrotron peak blazars (LSPs) could be the source of Changing-look blazars because 90.7\% of the Changing-look blazars in this work are confirmed as LSPs. An anti-correlation between $EW$ and continuum intensity, the so-called global Baldwin effect (BEff) has been confirmed. We suggest the steeper global BEff observed for blazar than for radio-quiet active galactic nuclei (RQ-AGNs) is caused by the inverse Compton scattering of broad-emission-line photons. This interpretation is further supported by the positive correlation between the emission line $EW$ and intrinsic inverse Compton luminosity., Comment: Accepted to ApJ

Reinforced concrete (RC) structures are generally deteriorated by penetration of water and gases that induce corrosion of reinforcements. Surface-penetrants, which increase gas-penetration resistance of concrete, can improve the long-term durability of RC members. A kind of surface-treatment, such as silane penetrants, gives a high water-repellant effect to concrete. It is well known that concrete in cold regions is occasionally damaged by freezing and thawing (F-T) cycles. In a microscopic viewpoint, water-pressure in pore structures of concrete increases due to freezing. The increase of internal water pressure may be a cause of the F-T damage of concrete. It is possibly hard to ease the water-pressure in saturated concrete incorporating the water-repellant penetrant. That is, the surface-treated concrete under the F-T cycles may deteriorate seriously. To examine the effect of surface-treatment, the study conducted the F-T test (JIS A 1148) by using concrete that was painted with surface-penetrants. The foci of this investigation are to examine the F-T durability of surface-treated concretes and to compare the effect of the surface-penetrants. This paper reports the effects of the water-repellant penetrant on the F-T durability.

Muscle contractures are a prominent and disabling feature of many neuromuscular disorders, including the 2 most common forms of childhood neurologic dysfunction: neonatal brachial plexus injury (NBPI) and cerebral palsy. There are currently no treatment strategies to directly alter the contracture pathology, as the pathogenesis of these contractures is unknown. We previously showed in a mouse model of NBPI that contractures result from impaired longitudinal muscle growth. Current presumed explanations for growth impairment in contractures focus on the dysregulation of muscle stem cells, which differentiate and fuse to existing myofibers during growth, as this process has classically been thought to control muscle growth during the neonatal period. Here, we demonstrate in a mouse model of NBPI that denervation does not prevent myonuclear accretion and that reduction in myonuclear number has no effect on functional muscle length or contracture development, providing definitive evidence that altered myonuclear accretion is not a driver of neuromuscular contractures. In contrast, we observed elevated levels of protein degradation in NBPI muscle, and we demonstrate that contractures can be pharmacologically prevented with the proteasome inhibitor bortezomib. These studies provide what we believe is the first strategy to prevent neuromuscular contractures by correcting the underlying deficit in longitudinal muscle growth.

Wireless physical layer key generation technology can effectively solve the problem of key distribution and management in traditional security mechanisms, and thus has been widely studied. In this paper, we propose a physical layer key generation scheme based on frequency hopping, which improves the key generation efficiency under the condition of static wireless channel with low physical layer key generation efficiency and low randomness. In addition, we apply the moving average and principal component analysis (PCA) of preprocessing methods to the channel characteristics, and perform double-threshold quantization to improve the consistency of the key generation. Finally, we verify the proposed key generation scheme on the hardware platform consisting of STM8L101 and CC1101. The experimental results show that when the frequency hopping step is 200KHz, the key agreement rate is higher than 99% and the key generation efficiency is 88%.

Purpose: Neonatal brachial plexus injury (NBPI) causes disabling contractures that cannot be fully prevented or corrected, largely because their pathophysiology is incompletely understood. Research in a mouse model has shown that contractures result at least in part from impaired postnatal muscle growth, but the mechanism of this impaired muscle growth is unknown. The current work uses a mouse model to experimentally assess and correct muscle protein imbalance (synthesis versus degradation) as a mechanism of impaired muscle growth and contractures following NBPI. Methods: Unilateral global (C5-T1) NBPIs were surgically created in 5-day-old mice, which permanently denervates the forelimb and reliably causes shoulder and elbow contractures 4 weeks post-NBPI. Protein synthesis was measured in denervated and contralateral control elbow flexor muscles within 4 weeks post-NBPI by incorporation of puromycin, a nucleoside analog, and by expression of major structural and contractile proteins by RNA-sequencing and Western blot. Protein degradation was similarly measured by K48-linkage specific polyubiquitin, an indicator of protein degradation by the proteasome pathway, and by expression of protein degradation markers by RNA-sequencing. Subsequently, to test the ability of proteasome inhibition to prevent contractures, bortezomib, a 20S proteasome inhibitor, was co-administrated with [Gly14]-Humanin G ([Gly14]-HN, to limit bortezomib toxicity) systemically for 4 weeks post-NBPI. Saline and [Gly14]-HN alone were administered separately as controls. Shoulder and elbow contractures were measured 4 weeks post-NBPI, and denervated and control elbow flexor muscles were assayed for 20S proteasome activity, volume and cross-sectional area (CSA) by microCT, and sarcomere length by DIC microscopy. Results: NBPI did not reduce muscle protein synthesis, measured either by puromycin incorporation or by RNA and protein levels of all major structural and contractile proteins. However, NBPI increased protein degradation, as indicated by a doubling of K48-linkage specific polyubiquitin and increased expression of Trim63/MurF1, a driver of proteasome-mediated protein degradation. Bortezomib + [Gly14]-HN effectively prevented contractures following NBPI compared to saline and [Gly14]-HN alone (p

Physical-layer secret key generation (PSKG) leveraging reciprocal wireless channel has been widely studied in pairwise communication scenarios as it addresses the key distribution problem in traditional security mechanisms. However, PSKG encounters the challenges of low key agreement, information leakage and high system cost when it is extended to produce a secret key for a group of users. In this paper, we propose a lightweight Group secret key generation approach leveraging Non-reconciled received Signal Strength (GNSS). Specifically, pairwise bit sequences with high similarity are firstly extracted and then a group key is securely shared with the protection of these pairwise bit sequences, which prevents the information leakage and sophisticated information reconciliation. Detailed algorithms of GNSS for star and chain networks are presented. Numerical and experimental results demonstrate that GNSS can provide high key agreement, thus enabling key generation technology to be used in a group communication scenario.

Radio frequency (RF) fingerprint identification of wireless communication equipment has developed rapidly. It is to extract the equipment's RF fingerprint from the equipment's communication signals, so as to realize the identification and authentication of the equipment. In this paper, we propose a novel method for identifying pseudo-Global Positioning System (GPS) signal based on RF fingerprint. In our proposed method, we apply the Doppler frequency shift as RF fingerprint, the pseudo GPS signal and the real GPS signal is identified by extracting the Doppler frequency shift from the signal. And the experimental results show that the Doppler frequency shift can be used as RF fingerprint to identify the pseudo GPS signal well.

Numerical methods were carried out on a turbocharger compressor with inlet bent pipe to research a novel clocking effect between the inlet bend and the volute. It was found that the clocking effect with 3.4 percent of variations (1.9 percentage points) in compressor efficiency positively exists at the research point near chock. The reason for the changed efficiency loss is that the inlet bend induces a serious distortion of approaching flow to impeller inlet on one hand, and the downstream volute causes a circumferentially non-uniform distribution of pressure in vaneless diffuser. By adjusting the clocking positions between inlet bend and volute, not only is the unsteadiness of the flow rate through single impeller channel changed, but the uniformity of the incoming flow at the vaneless diffuser inlet is modulated as well. It is the dominant reason for the novel clocking effect that the bad uniformity causes more flow loss in both diffuser and volute.

Physical-layer secret key generation (PSKG) technology based on reciprocal wireless channel has been widely studied in point-to-point (P2P) scenarios as it can effectively solve the key distribution problem in traditional security mechanisms. However, the computation and energy cost of PSKG is high when it is extended to group key distribution. The problem of applying PSKG to ensure group secret communication remains open. In this paper, we propose a lightweight group key distribution (LGKD) method for a star network topology environment. In our proposed method, center node and each child node first extract high correlated channel characteristics instead of generating identical P2P keys, respectively. Then, the group key is broadcasted to each child node protected by the P2P channel characteristics with high similarity. Our simulation results verify the feasibility and effectiveness of our proposed group key distribution method.

Variable geometry turbine (VGT) has been widely applied in internal combustion engines to improve the engine transient response and torque at low speed. One of the most popular variable geometry turbine is the variable nozzle turbine (VNT), in which the nozzle vanes can be rotated along the pivoting axis and thus the flow passage through the nozzle can be adjusted to match with different engine operating conditions. One disadvantage of the VNT is the turbine efficiency degradation due to the leakage flow in the nozzle endwall clearance, which is needed to allow the nozzle vanes to rotate without sticking. Especially at small nozzle open condition, there is large loading on the nozzle and high pressure gradient between the nozzle pressure and suction side. Strong leakage flow exists inside the nozzle endwall clearance from pressure side to suction side, leading to large flow loss and turbine stage efficiency degradation. In the present paper, a novel split sliding variable nozzle turbine (SSVNT) has been proposed to reduce the nozzle leakage flow and to improve turbine stage efficiency. The idea is to divide the nozzle into two parts: one part is fixed and the other part can slide along the partition surface. The mechanism of nozzle flow passage variation in SSVNT is different from that of the traditional pivoting VNT. The sliding vane and the fixed vane together form an integrated vane. The flow of the turbine is determined by the passage of the integrated vanes. When moving the sliding vane to large radius position, the nozzle flow passage opens up and the turbine has high flow capacity. When moving the sliding vane towards small radius position, the nozzle flow passage closes down and the turbine has low flow capacity. As the fixed vane doesn’t need endwall clearance, there is no leakage flow inside the fixed vane and the total leakage flow through the integrated vane can be reduced. Based on calibrated numerical modeling, the analysis results showed that there is up to 12% turbine stage efficiency improvement with the SSVNT design at small nozzle open condition while maintaining the same flow capacity and efficiency at large nozzle open condition, compared to the conventional VNT. The mechanism of efficiency improvement in the SSVNT design has also been discussed.

Soil salinity and sodicity can significantly reduce the value and the productivity of affected lands, posing degradation, and threats to sustainable development of natural resources on earth. This research attempted to map soil salinity/sodicity via disentangling the relationships between Landsat 8 Operational Land Imager (OLI) imagery and in-situ measurements (EC, pH) over the west Jilin of China. We established the retrieval models for soil salinity and sodicity using Partial Least Square Regression (PLSR). Spatial distribution of the soils that were subjected to hybridized salinity and sodicity (HSS) was obtained by overlay analysis using maps of soil salinity and sodicity in geographical information system (GIS) environment. We analyzed the severity and occurring sizes of soil salinity, sodicity, and HSS with regard to specified soil types and land cover. Results indicated that the models’ accuracy was improved by combining the reflectance bands and spectral indices that were mathematically transformed. Therefore, our results stipulated that the OLI imagery and PLSR method applied to mapping soil salinity and sodicity in the region. The mapping results revealed that the areas of soil salinity, sodicity, and HSS were 1.61 × 106 hm2, 1.46 × 106 hm2, and 1.36 × 106 hm2, respectively. Also, the occurring area of moderate and intensive sodicity was larger than that of salinity. This research may underpin efficiently mapping regional salinity/sodicity occurrences, understanding the linkages between spectral reflectance and ground measurements of soil salinity and sodicity, and provide tools for soil salinity monitoring and the sustainable utilization of land resources.

Purpose We used an established mouse model of elbow flexion contracture after neonatal brachial plexus injury (NBPI) to test the hypothesis that preservation of afferent innervation protects against contractures and is associated with preservation of muscle spindles and ErbB signaling. Methods A model of preganglionic C5 through C7 NBPI was first tested in mice with fluorescent axons using confocal imaging to confirm preserved afferent innervation of spindles despite motor end plate denervation. Preganglionic and postganglionic injuries were then created in wild-type mice. Four weeks later, we assessed total and afferent denervation of the elbow flexors by musculocutaneous nerve immunohistochemistry. Biceps muscle volume and cross-sectional area were measured by micro computed tomography. An observer who was blinded to the study protocol measured elbow flexion contractures. Biceps spindle and muscle fiber morphology and ErbB signaling pathway activity were assessed histologically and immunohistochemically. Results Preganglionic and postganglionic injuries caused similar total denervation and biceps muscle atrophy. However, after preganglionic injuries, afferent innervation was partially preserved and elbow flexion contractures were significantly less severe. Spindles degenerated after postganglionic injury but were preserved after preganglionic injury. ErbB signaling was inactivated in denervated spindles after postganglionic injury but ErbB signaling activity was preserved in spindles after preganglionic injury with retained afferent innervation. Preganglionic and postganglionic injuries were associated with upregulation of ErbB signaling in extrafusal muscle fibers. Conclusions Contractures after NBPI are associated with muscle spindle degeneration and loss of spindle ErbB signaling activity. Preservation of afferent innervation maintained spindle development and ErbB signaling activity, and protected against contractures. Clinical relevance Pharmacologic modulation of ErbB signaling, which is being investigated as a therapy for congestive heart failure, may be able to recapitulate the protective effects of afferent innervation in spindle development and contracture prevention. Muscle spindle preservation may also have implications in proprioception and motor learning, both of which are impaired in NBPI.

Radial flow Variable Nozzle Turbine (VNT) enables better matching between a turbocharger and engine, and can improve the engine performance as well as decrease the engine emissions, especially when the engine works at low-end operation points. With increased nozzle loading, stronger shock wave and clearance leakage flow may be generated. The shock wave consequently introduces strong rotor-stator interaction between turbine nozzle and impeller, which is also a key concern of impeller high cycle fatigue failure. With the purpose of developing a shock wave free or low shock wave intensity turbine nozzle, the influence of grooved vane on the shock wave characteristics is investigated in present paper. A Schlieren visualization experiment was first carried out on a linear turbine nozzle with smooth surface and the behavior of the shock wave was studied. Numerical simulations were also performed on the turbine nozzle. The predicted shock wave shape, position and intensity were compared against the Schlieren images. Guided by the visualization and numerical simulation, grooves were designed on the nozzle surface where the shock wave was originated and numerical simulations were performed to investigate the influence of grooves on the shock wave characteristics. Results indicate that for a smooth nozzle configuration, the intensity of the shock wave increases as the expansion ratios increase, while the onset position is shifted downstream to the nozzle trailing edge. For a nozzle configuration with grooved vane, the position of the shock wave onset is shifted upstream compared to the one with a smooth surface configuration, and the intensity of the shock wave as well as the static pressure distortion at the nozzle vane exit plane are significantly depressed.

The superimposed influences of the blade rows in a multistage compressor are important because different matches of upstream and downstream blades can result in significant differences in the stator wake oscillation. Numerical investigation of the axial stator wake oscillation, which is affected upstream by the axial rotor and downstream by the radial rotor, was performed in an axial-radial combined compressor. Many configurations with different blade numbers and locations, which influence axial stator wake oscillation were investigated. When rotors have equal blade numbers, the axial stator wake oscillates periodically versus time within time T (moving blade passing 1/3 revolution). In contrast, stator wake oscillates irregularly within T when rotors have different blade numbers. A model-split subtraction method is presented in order to separate the influences of the individual blade rows on the wake oscillation of the axial stator. Analysis from the rotor-stator configuration showed that the unsteady flow angle fluctuation response is caused by the upstream rotor. For the rotor-stator-rotor configuration, the unsteady flow angle fluctuations are influenced by up- and downstream blade rows. With the model-split subtraction method, the up- and downstream influences on the flow angle fluctuation could be clearly separated and quantified. Low amplitudes could be observed when the influences from up- and downstream moving rows were superimposed with the “positive peak-negative peak” type wave. Clocking investigations were carried out to change the relative superimposed phase of influences from the surrounding blade rows in order to modulate the amplitudes of the axial stator wake oscillation. However, the amplitudes did not reach the maximum when they were superimposed with “positive peak-positive peak” type wave due to the impact of the interaction between the two moving blade rows.

Fractures play a vital role in the exploration and development of shale oil and gas by providing effective space for shale reservoirs and significantly improving the fluid flow capability. Core observations, microscopic analyses of thin sections, scanning electron microscopy, and Formation MicroScanner Imaging (FMI) were used to determine the types, causes of formation, and development characteristics of the fractures in lacustrine shale reservoirs in the lower part of the Paleogene Shahejie Formation (Es 3 ) in the Zhanhua Depression, Bohai Bay Basin, eastern China. X-ray diffraction (XRD) analysis, total organic carbon (TOC) measurements, and porosity and permeability measurements were used to study the controlling factors of the fractures in the shale reservoirs, and to analyze the impact of the fractures on the shale reservoirs properties and subsequent exploration and development. The studied shale reservoir mainly displays tectonic fractures as well as various types of non-tectonic fractures. The non-tectonic fractures mainly include over-pressure fractures, diagenetic fractures, inter-layer bedding fractures, and fractures of mixed origins. In the study area, the tectonic fractures which were formed under the combined action of tensile and shear stress display the following characteristics. The dip angle of the tectonic fractures varies significantly. Unfilled or half-filled effective fractures have a high proportion. These fractures are mainly oriented in the NE–SW, NNE–SSW, and WNW–ESE directions, with fractures in the NE–SW direction accounting for the highest proportion. The tectonic and non-tectonic fracture development is affected by multiple types of factors such as the presence of faults, mineral composition, lithology, abnormal pressure and organic matter content. Abnormally high pore pressure is a very important factor in the development of non-tectonic fracture. It is inferred that the over-pressure is mainly related to hydrocarbon generation during thermal evolution. Fractures effectively improve the porosity and permeability of the shale reservoirs, and the enhancement of permeability is particularly significant. The current stress field affects the fluid flow capability of the fracture reservoirs, and the present maximum principal stress in Zhanhua Depression is oriented in the NEE–SWW direction, which has a small angle with fractures in NE–SW direction. We propose that the fractures in this direction have the greatest connectivity and thus are a high-priority target for petroleum exploration and development.

A turbocharger compressor with a wide flow range and a high efficiency is important to the application of advanced clean combustion technologies, such as homogeneous charge compression ignition and low-temperature combustion, in diesel engines. Self-recirculation casing treatment is one of the techniques that can extend the compressor surge margin without much efficiency penalty. The underlying physics of the self-recirculation casing treatment technology were investigated with computational fluid dyamics modeling and bench testing in this study. It is identified that, if the bleed slot of the self-recirculation casing treatment is located upstream of the impeller passage’s throat area, self-recirculation casing treatment improves the surge margin but the throat still limits the maximum flow capacity of the compressor. On the other hand, if the bleed slot of the self-recirculation casing treatment is located at the impeller passage’s throat area, the self-recirculation casing treatment improves the maximum flow capacity but results in a significant compressor efficiency penalty in the low-flow range. An active self-recirculation casing treatment design was proposed. The active self-recirculation casing treatment design extends the compressor flow capacity and improves the surge margin without an efficiency penalty through dual bleed slots with one upstream and the other downstream of the leading edge of the splitter blades. In the choke condition, the upstream bleed slot will be closed; near the surge condition, the downstream bleed slot will be closed. In the middle flow range, both bleed slots are closed. Both the numerical data and the bench testing results show that the maximum flow rate could be extended by about 15% and the surge margin by about 20% without an efficiency penalty. The mechanism of the performance improvement is also numerically studied.

With high spatial resolution of ultrasonic location and high sensitivity of optical detection, ultrasound-modulated optical tomography (UOT) is a promising noninvasive biological tissue imaging technology. In biological tissue, the ultrasound-modulated light signals are very weak and are overwhelmed by the strong unmodulated light signals. It is a difficulty and key to efficiently pick out the weak modulated light from strong unmodulated light in UOT. Under the effect of an ultrasonic field, the scattering light intensity presents a periodic variation as the ultrasonic frequency changes. So the modulated light signals would be escape from the high unmodulated light signals, when the modulated light signals and the ultrasonic signal are processed cross correlation operation by a lock-in amplifier and without a chopper. Experimental results indicated that the signal-to-noise ratio of UOT is significantly improved by a lock-in amplifier, and the higher the repetition frequency of pulsed ultrasonic wave, the better the signal-to-noise ratio of UOT.

Aging is a very important issue not only in dermatology, but also cosmetic science. Cutaneous aging involves both chronological and photoaging aging process. The evaluation and classification of aging is an important issue with the medical cosmetology workers nowadays. The purpose of this study is to assess chronological-age-related and photo-age-related of human skin. The texture features of skin surface skin, such as coarseness, contrast were analyzed by Fourier transform and Tamura. And the aim of it is to detect the object hidden in the skin texture in difference aging skin. Then, Support vector machine was applied to train the texture feature. The different age’s states were distinguished by the support vector machine (SVM) classifier. The results help us to further understand the mechanism of different aging skin from texture feature and help us to distinguish the different aging states.

An effective measure to improve the surge margin of a centrifugal compressor, without sacrificing efficiency, is to implement a recirculating casing treatment inside the compressor cover. However, introduction of an additional sound propagation path directly over the rotating impeller blades exposes the inherently unsteady internal flow-field as an added potential noise source, which is of concern for automotive applications. The present study conducts performance and acoustic measurements of a new compressor which was designed to achieve high isentropic efficiency over a wide flow range, featuring an impeller with splitter blades and a vaneless diffuser. A dual-port active casing treatment (ACT) was also incorporated into the compressor cover to independently extend both the low and high flow rate operating regions of the compressor. The slot of the first (surge) port is positioned between the main and splitter blades of the impeller, similar to passive casing treatments that are already widely adopted. This port extends the low-flow boundary of the compressor operating range by reducing flow separation on the suction surface of the main blades near the shroud. The slot of the second (choke) port is located just behind the splitter blades, and it is studied in both the open and closed positions. This second port allows for increased air flow near choke, due to the slot position just downstream of the aerodynamic throat of the compressor. The current ACT design leaves the surge port open at all times, while the choke port is only opened when the compressor operates near choke conditions. In addition to comparing experimental results from this new compressor in both configurations (choke port open and closed), measurements from a comparable (baseline) compressor without splitter blades and a single-port shroud are utilized to assess the acoustics of the new design. Acoustic measurements were completed over the low to mid-speed operating range, which is a region heavily weighted in customer drive cycles for light and medium duty vehicles. The conscientious design of the impeller and surge slot of the new compressor to minimize flow separation on the suction surface of the inducer blades is shown to not only improve efficiency and extend the low-flow operating range, but (with the choke port closed) broadband noise is significantly reduced in the mid to high flow rate operating region. At low flow rates, the new compressor (with the choke port closed) is slightly louder than the baseline compressor at the inlet duct measurement location, but essentially equal to the baseline compressor at the external microphone location near the compressor inlet duct opening. When the choke port of the new compressor is open, broadband noise increases slightly relative to the closed configuration. More importantly, the peak sound pressure level at (main) blade-pass frequency is reduced by opening the choke port, and the operating region of elevated tonal noise shifts from mid to high flow rates.

In our study, the skin canceration processes induced by UVB were analyzed from the perspective of tissue spectrum. A home-made Raman spectral system with a millimeter order excitation laser spot size combined with a multivariate statistical analysis for monitoring the skin changed irradiated by UVB was studied and the discrimination were evaluated. Raman scattering signals of the SCC and normal skin were acquired. Spectral differences in Raman spectra were revealed. Linear discriminant analysis (LDA) based on principal component analysis (PCA) were employed to generate diagnostic algorithms for the classification of skin SCC and normal. The results indicated that Raman spectroscopy combined with PCA-LDA demonstrated good potential for improving the diagnosis of skin cancers.

Global climate change projections suggest an increasing frequency of droughts and extreme rain events in the steppes of the Eurasian region. Using the eddy covariance method, we measured carbon and water balances of a meadow steppe ecosystem in Northeast China during 2 years which had contrasting precipitation patterns in spring seasons in 2007 and 2008. The meadow steppe sequestrated only 64Ð2 gC m 2 year 1 in 2007 compared to 160Ð5 gC m 2 year 1 in 2008, due to a severe spring drought in 2007. The 2007 spring drought resulted in a dramatic reduction of leaf area index (LAI) and aboveground net primary productivity (ANPP). However, the meadow steppe still acted as a carbon sink in 2007. The strength of the sink was much greater than that in the typical steppes in Central Mongolia and Inner Mongolia. Spring drought also caused a reduction of plant transpiration (Tr) and total ecosystem evapotranspiration (ET). However, the suppression of ET in 2007 was relatively small in comparison to gross ecosystem productivity (GEP) reduction. Thus, ecosystem water use efficiency (WEU) (GEP/ET) in 2007 was reduced to 5Ð0 gCO2 kg 1 H2O or 75% of that of 2008. We concluded that spring drought detrimentally impacted meadow steppe ecosystem by reducing leaf areas, biomass, GEP, WUE and associated increases in soil evaporation (Es) that might aggravate soil salinization of the Songnen Plain. Copyright  2011 John Wiley & Sons, Ltd.

Over the past three decades, China’s economic growth has been the fastest among major nations. However, its environmental degradation has also accelerated (Liu and Diamond 2008). To mitigate the degraded environment, China has been implementing large-scale conservation programs, including the Key Shelterbelt Construction Program, Beijing-Tianjin Sandstorm Control Program, Wildlife Conservation and Nature Reserve Development Program (Ouyang 2007), Forest Eco-Compensation Program (Ministry of Finance of China and State Forestry Administration of China 2007), the Natural Forest Conservation Program, and the Grain to Green Program (Zhang et al. 1999; Xu et al. 2006; Liu et al. 2008). The Three-River Headwater (TRH, Sanjiangyuan, Fig. 1) region is located in the core of the Tibet Plateau, China, and covers 363,000 km2 with the average altitude of 4,200 m. It is the world’s highest altitude region with the richest biodiversity, and contains China’s highest elevation and largest area wetlands (Committee 2009). The TRH region, known as China’s, and even Asia’s water tower, is the headstream of the Yangtze River (Chang Jiang, the longest river in China and the third longest in the world), the Yellow River (Huang He, the second longest river in China, referred to as the cradle of the Chinese civilization), and the Lantsang River (Lancang Jiang, an international river called the Mekong River outside China). This region provides 25% of the water volume of the Yangtze River, 49% of the Yellow River, and 15% of the Lantsang River (Qin et al. 2008). In 2000, the Chinese government established the TRH reserve with an area of 152,300 km2—a land area larger than England and Wales combined, to protect this most unique and fragile ecosystem. Fig. 1 China’s water tower. Based on the MODIS product (MOD09AlV5), 12 August 2008 The TRH region suffers from global warming and the explosive increase in the intensity and extent of human activities (overgrazing, poaching of plants and wildlife, gold mining, etc.) (Zhao and Zhou 2005). Rangelands are severely overgrazed, and 58% of rangelands are moderately to severely degraded. Soil erosion has deteriorated about 26.5% of the region’s total land area. Rat infestation is widespread and the number of mouse-hole per hm2 is 1,335. Draught-up days of rivers are increasing (Lu 2007). The average annual runoff decreased more than 20% during the past 50 years (Qinghai Provincial Government 2005). Nearly one-fifth of its species are threatened (Cai 2008). The environmental degradation is also causing economic losses, and even brought about so-called “ecological refugees.” For example, Maduo County was one of the richest counties of the country in the early 1980s; however, it is now one of the 10 poorest counties, mainly due to ecological degradation caused by overgrazing (Gu et al. 2005). The deteriorating ecosystems prompted China to take an unprecedented conservation action—the Ecological Protection and Restoration Program (EPRP) in the TRH region in 2005 (Engineering Consulting Center of Qinghai Province 2005). The EPRP conserves and rehabilitates ecological functions through ecological migration, grazing bans, wetland protection, and harnessing degraded grassland. The EPRP is regarded as another large landmark project after the Development of the West Regions and the Qinghai–Tibet Railway. The Ecological Migration Program (EMP) among the EPRP in the TRH region, meaning local residents should move out from the reserve to restore the ecosystem and protect the environment, is deemed the country’s largest scale ecological migration for ecological compensation. A total of 7,500 million yuan (at present, $1 U.S. = 6.8 yuan) was budgeted for the EPRP, and 1,500 million yuan was allocated for the EMP. By the end of this program in 2010, almost all local Tibetan race residents are expected to be relocated to protect the vulnerable environment.

The Songnen Plain in Northeast China, one of the key national bases of agricultural production, went through remarkable land use/cover changes in recent years. This study aimed to explore the long-term land use/cover changes and the effects of these changes on the environment. The Landsat-based analysis showed that, during 1986–2000, cropland, built-up land and barren land had increased, among which cropland had the largest increase of 9,198km2 with an increase rate of 7.5%. Woodland, grassland, water body and swampland had decreased correspondingly, among which grassland had the most dramatic decrease of 6,127km2 with a decrease rate of 25.6%. The transition matrix results revealed that grassland, woodland and swampland were the three main land use types converted to cropland. Climate warming created the potential environment for the conversion of grassland and swampland into cropland. Land resources policy made by central and provincial governments of China affected the pattern and intensity of land use. Land use/cover changes accompanied by climatic variation brought out a series of environmental consequences, such as sand desertification of land, land salinization and alkalinization, grassland degradation, and more frequent floods. Under this circumstance, optimized land use structure and restoration measures are needed.

The current study addressed the spatial variation of soil organic matter (SOM), total nitrogen (TN), extractable phosphorus (EP), and extractable potassium (EK) in agricultural soils of a representative region, northeast China. Soil cation exchange capacity (CEC) and the effects of landscape attributes and land use were also investigated. The techniques used included conventional statistics, geostatistics, and geographic information systems (GIS). Our study demonstrated that EP had the greatest coefficient of variation (CV), and CEC had the least CV. The experimental semivariograms of the five soil chemical properties included in this study were all fitted with exponential models. The five soil variables all showed moderate spatial dependence. The SOM, EK, and CEC decreased with increasing altitude. Significant negative relationships were found between the slope gradient and EP, EK, and CEC. Relatively steeper slopes might result in greater soil erosion, which leads to a decline in soil nutrients. Soil ty...

In the past century, especially the past five decades, the grasslands of the West Songnen Plain, Northeast China, were rapidly converted into croplands and salinized wasteland, and experienced a fragmentation process that is still ongoing. Almost no information is available on the spatial-temporal changes of grasslands in this area. In this study, grassland cover change, agricultural reclamation and salinized wasteland expansion were investigated during the past five decades. Grassland fragmentation was studied based on four landscape metrics. The grassland cover change was detected from a time series of topographic maps from 1954, satellite images of Landsat TM in 1986, 1995, and 2000 using remote sensing and geographic information systems (GIS). In addition, the land use changes were analyzed using a transition matrix of land use types, while the driving forces were explored according to climatic changes and socioeconomic developments. The results indicated a significant decrease in grassland area. Of the 1 418 945 ha of native grassland in 1954, approximately 64% was removed by 2000, while the number of patches (NP) increased from 865 to 2035 and the mean patch size (MPS) decreased from 1640 ha to 252 ha. During the whole study period, the average annual decrease rate of grassland was 34 894 ha/year. Cropland and salinized wasteland were the two main land use types into which grassland converted. During the past decades, obvious climatic changes occurred, which supplied a favorable potential environment for agricultural development but damaged grassland productivity. On the other hand, population, GDP and livestock number increased significantly as grassland quality decreased. According to the results, the shrinkage and fragmentation of grasslands may well be explained by socioeconomic development and aided by changing climatic conditions.

The ultimate goal of an advanced turbocharger development is to have a superior aerodynamic performance while having the turbocharger survive various real world customer applications. Due to the uncertainty of customer usage and driving pattern, the fatigue life prediction is considered one of the most ambiguous analyses in the entire design and analyses processes of the turbocharger. The turbocharger system may have various resonant frequencies, which may be within the range of turbocharger operation for automotive applications. A turbocharger may operate with excessive stresses when running near resonant frequencies. The turbocharger may experience fatigue failures if the accumulative cycles of the turbocharger running across the resonant frequencies exceeds a certain limit. In this study, the authors propose an alternative approach to mitigate this kind of fatigue issues: i.e. engine system approach to improve turbocharger fatigue life via avoiding operating the turbocharger near resonant speeds for extended period of time. A preliminary numerical study was made and presented in this paper to assess the feasibility of such an engine system approach, which is followed by an engine dynamometer test for engine performance sensitivity evaluation when the turbocharger operation condition was adjusted to improve the high cycle fatigue life. The study shows that for a modern diesel engine equipped with electrically controlled variable geometry turbine and EGR for emission control, through the engine calibration and control upgrade, turbocharger operation speed can be altered to stay away from certain critical speeds if necessary. The combined 1D and 3D numerical simulation shows the bandwidth of the turbine “risk zone” near one of the resonant speeds and the potential impact on engine performances if the turbocharger speed has to be shifted out of the “risk zone.”

As inlet bent-pipes are often used in vehicle turbocharger compressors, understanding of the inlet bent-pipe’s effect on centrifugal compressor and the mechanism of flow loss is important to improve the turbocharger compressor performance. Experiment and numerical simulation were carried out on a centrifugal compressor with straight pipe and bent-pipe. Numerical simulated compressor performance was compared with test data obtained from compressor flow bench test and to validate the numerical method. The analysis is mainly based on numerical results and it indicated that the inlet bent pipe induces a serious distortion at impeller inlet and increases the risk of blade high-cycle fatigue. The level of distortion changes to be more serious as the operation point of compressor varies from design point to high load. When an impeller channel enters distortion, the larger pressure difference between inlet and outlet makes this channel get clogged and the flow rate through this channel is reduced. At design point the bent pipe mainly influences the flow loss in the inlet pipe and impeller while at high load more serious flow distortion induced by bent-pipe is able to extend its stronger effect to the downstream diffuser and volute.Copyright © 2014 by ASME

Heavy EGR required on diesel engines for future emission regulation compliance has posed a big challenge to conventional turbocharger technology for high efficiency and wide operation range. This study, as part of the U.S. Department of Energy sponsored research program, is focused on advanced turbocharger technologies that can improve turbocharger efficiency on customer driving cycles while extending the operation range significantly, compared to a production turbocharger. The production turbocharger for a medium-duty truck application was selected as a donor turbo. Design optimizations were focused on the compressor impeller and turbine wheel. On the compressor side, advanced impeller design with arbitrary surface can improve the efficiency and surge margin at low end while extending the flow capacity, while a so-called active casing treatment can provide additional operation range extension without compromising compressor efficiency. On the turbine side, mixed flow turbine technology was revisited with renewed interest due to its performance characteristics, i.e. high efficiency at low-speed ratio, relative to the base conventional radial flow turbine, which is relevant to heavy EGR operation for future diesel applications. The engine dynamometer test shows that the advanced turbocharger technology enables over 3% BSFC improvement at part-load as well as full-load condition, in addition to an increase in rated power. The performance improvement demonstrated on engine dynamometer seems to be more than what would typically be translated from the turbocharger flow bench data, indicating that mixed flow turbine may provide additional performance benefits under pulsed exhaust flow on an internal combustion engine and in the low-speed ratio areas that are typically not covered by steady state flow bench tests.

While horizontal gradients of biodiversity have been examined extensively in the past, vertical diversity gradients (elevation, water depth) are attracting increasing attention. We compiled data from 443 elevational gradients involving diverse organisms worldwide to investigate how elevational diversity patterns may vary between the Northern and Southern hemispheres and across latitudes. Our results show that most elevational diversity curves are positively skewed (maximum diversity below the middle of the gradient) and the elevation of the peak in diversity increases with the elevation of lower sampling limits and to a lesser extent with upper limit. Mountains with greater elevational extents, and taxonomic groups that are more inclusive, show proportionally more unimodal patterns whereas other ranges and taxa show highly variable gradients. The two hemispheres share some interesting similarities but also remarkable differences, likely reflecting differences in landmass and mountain configurations. Different taxonomic groups exhibit diversity peaks at different elevations, probably reflecting both physical and physiological constraints.

A new hypothesis is presented for the superimposed effects of the blade pressure distribution in a multistage compressor. The effects of the unsteady pressure fluctuations on the blade surface are separated into three groups. The influences of the upstream or downstream rotors can be obtained by numerical simulation for the R/S or S/R configuration; the data produced by all the influences can be obtained from the R/S/R configuration. The effects of the blade counts and clocking on the superimposed effects, acting on the profile pressure distribution, are studied using a special data analysis method that had been previously developed by the authors. The results indicate that the blade counts of the upstream and downstream rotors determine the periods of the unsteady pressure fluctuations on the stator surface. The clocking moving blade rows modulate the relative superimposed phases and interactions between two rotors such that the unsteady pressure fluctuates with different amplitudes on the surface of the stator blade.Copyright © 2013 by ASME