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Mechanically pumped two-phase loop (MPTL) is an advanced two-phase heat transfer device through the release of latent heat of phase change during flow boiling process. In order to investigate the performance of MPTL system under different gravity conditions, one MPTL setup using a novel two-phase thermal-controlled accumulator coupled with self-cooling function was designed and constructed. Its characteristics of startup, phase change, and temperature control were tested on the ground and on orbit. Test results showed that MPTL system had good working performance and stable working characteristics both on the ground and on a satellite. The functions of fluid management, temperature control and self-cooling for accumulator were verified under different gravity conditions. It was found that the superheat time and superheat temperature for on-orbit results were longer and higher than the ground's results respectively. The heat transfer efficient of two-phase flow of MPTL system could reach 12,000 − 60,000 W/(m2·K). Affected by the buoyancy, the heat transfer coefficient on-orbit was 10%−29% lower than the ground result. The research would contribute to the theoretical basis of two-phase flow and heat transfer and promote the development of active two-phase thermal control technology for space. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau is an important area for studying global climate change, but the answers to many scientific problems remain unknown. Here, we present new information from the lacustrine sedimentary record in the western Tibetan Plateau, related to the third most‐recent glaciations. Continuous sediment data, including sporopollen, particle size, total organic carbon, mass susceptibility, CaCO3, CaSO4, BaSO4 contents and chronological data, were reconstructed and revealed that climate and environmental conditions obviously and distinctly changed between 600 and 700 thousand years ago. In comparison, the data obtained from the Guliya ice core in this area also corresponds to the global glacial climatic characteristics recorded in basin sediments in the eastern and southeastern regions of the plateau and to the information obtained from ice cores in the Antarctic and Arctic regions. In this study, we conclude that the main reason for the glaciations and new tectonic movement must be a geomagnetic polarity reversal 774 thousand years ago (from Matuyama to Brunhes). Indeed, the results of this study suggest that the described reversal event might have influenced the current global climate pattern and will continue to impact climatic changes in the future. [ABSTRACT FROM AUTHOR]

Abstract Huygens put forward his wave theory of light in as early as the 17th century, and he explained the process of light propagation with wavelet envelopes. So far, Huygens' principle has served as an explanation of the light propagation process and is mainly applied in the research of light diffraction. From the point of physics process, Huygens' principle transforms the process of light propagation into that of light radiation. We analyze the Huygens' principle from the wave equation. We find that its mathematical essence is the transformation among the different solutions of the wave equation. Built on the mathematical nature of the Huygens' principle, the direction, amplitude and phase of the Huygens wavelet were studied. Referring to the Poynting vector of electromagnetic waves, the tilt factor of the Huygens wavelet was obtained by vector analysis. Then according to the properties of plane waves and the Fresnel zone method and using the self-consistent principle, we lead to the conclusions that the phase of the Huygens wavelet is π/2 advanced of the incident light, and the wavelet amplitude is inversely proportional to the wavelength of the light. Finally, the relationship between wave optics and the primitive function is discussed. [ABSTRACT FROM AUTHOR]

We used Huygens’ principle to study the interaction between light and atom, and revealed the microcosmic process of the attenuation and gain of a plane wave. We began with the shadow of a leaf, expanding to the atomic absorption plane wave, and obtained the expression of the atomic absorption photon by using Huygens’ principle. Also the method of negative absorption is used to analyze the optical gain process, and we obtained the properties of a stimulated radiation photon according to the fact that the optical gain is atomic collective contribution of the stimulated radiation, the result shows that the atomic stimulated radiation is not photons cloning. [ABSTRACT FROM AUTHOR]

Stimulated emission is a process by which an incoming photon induces an excited atom to release a new photon. Current perspective believes that the new photon has an identical state as the incident one. However, it has contradictions with basic principles of quantum mechanics and an optical gain process. Analyzing gain processes by wave optics we discover that the stimulated emission superposition of the atomic ensemble is in phase with the incident wave, while the emission from a single atom is π/2 phase advanced. We show that conclusions consisting with laser gain processes can be obtained from this cognition. [ABSTRACT FROM AUTHOR]

Abstract: The suitability of three different two-equation turbulence models in predicting film cooling effectiveness on a rotating blade was investigated and they are the commonly used standard k-ε model, the k-ω model and the shear stress transport k-ω model. To fulfill this target, both numerical simulation and the experimental investigation were carried out for a rotating blade having a flat test surface with a 4mm diameter straight circular cooling hole in 30° inclined injection. The blade rotated at five different speeds of 0, 300, 500, 800 and 1000rpm. The momentum ratio was set to be 0.285 and the Reynolds (Re D) number based on the mainstream velocity and hydraulic diameter of the mainstream channel is 1.45×105. The averaged density ratio was chosen to be 1.026 with air as both the coolant and the mainstream. Comparison between the numerical work and the experimental results indicated that (1) the rotating speed is the most critical parameter influencing the film cooling effectiveness distributions and the pressure surface could be remarkably different from the suction surface, (2) as for the algebraic averaged film cooling effectiveness, numerical predictions of the three turbulence models all overshoot compared with the experimental results, (3) among the three turbulence models, the standard k-ε model gave the poorest prediction. [Copyright &y& Elsevier]

Rayleigh scattering is an elastic scattering. The scattering particles do not change the amplitude of the incident light wave, so they must affect the phase of the light wave. In this paper, the microscopic dielectric sphere is used as the scattering particle model to study the modulation of the phase of the light wave by the scattering particles. The paper analyzes the influence of micro-particles on the optical path, and obtains the phase of the light wave according to the wavelength of the incident light and the particle parameters. According to the Huygens principle, the light scattering of the particles is studied by diffraction method, and the scattered light intensity is proportional to the particle volume and inversely proportional to the fourth power of the light wavelength. In view of the uneven refractive index of the actual optical medium, this paper uses the graded index microsphere model for equivalent. The modulation of the phase of the light-wave by the graded-index particles and the influence on the optical path are studied. Finally, using the Huygens principle, the scattering properties of the refractive index inhomogeneous region are obtained. The work of this paper provides a new method for light scattering research. [ABSTRACT FROM AUTHOR]

For the purpose of dissipating large heat power with cyclical operating modes of satellite, one mechanically pumped two-phase loop (MPTL) coupled with a novel phase change energy storage device was designed and constructed. The phase change energy storage device integrating with filament tube heat exchanger and form-stable phase change material (PCM) with expanded graphite (EG) was designed and employed to increase the conductivity. The two-phase change behavior of liquid-vapor change for MPTL and solid-liquid transition for PCM was used to acquire, transport and store the heat. Results indicated that the time of heat storage for PCM device was more than 598.0 s, and the temperature at the outlet of the device increased from −2.0 °C to 15.0 °C under the heating power of 6.7 kW. The flowrate decreased from 0.059 kg/s to 0.034 kg/s due to the length increase of two-phase section during the melting process of PCM device. Lowering the rotation speed of pump increased the oscillating amplitude of flowrate, and its maximum value reached to 0.008 kg/s. The total working period for PCM device for lower rotation speed of 8000 r/min was 48.0 s longer than that for higher speed of 10000 r/min due to decreased heat transfer coefficient. [ABSTRACT FROM AUTHOR]

Utilizing the frequency selection characteristic of ring resonators, self-injection-locking linewidth narrowing and frequency stabilization of distributed feedback laser diodes (DFB-LDs) can be achieved under the aid of ring resonators. In this paper, the self-injection-locking effects of a DFB-LD realized by two fiber ring resonators and an optical waveguide ring resonator are compared. The influences of the resonant peak bandwidth and transmission on linewidth narrowing are demonstrated. It is shown that the mode hopping can be significantly suppressed by employing the optical waveguide ring resonator. This is of great significance for practical applications and integration of the self-injection-locked DFB-LDs. [ABSTRACT FROM AUTHOR]

Background: Patent foramen ovale (PFO) and obstructive sleep apnea (OSA) are independent risk factors for young conscious stroke which may also be concomitant symptoms with it. But there is no sufficient attention on these phenomena.Objective: To investigate the relationship between PFO, OSA and young stroke, and to look for proper treatment.Methods: Three patients with young conscious stroke were reported, each of them was combined with PFO and OSA. All patients were diagnosed as wake-up stroke (WUS). Contrast-enhanced transcranial doppler ultrasound (c-TCD) and polysomnography (PSG) test were used for auxiliary diagnosis.Results: Right-to-left shunts and moderate to severe sleep apnea were observed. Increased body mass index (BMI), hemoglobin (HGB) and hematocrit (HCT) index were also observed. After continuous positive airway pressure (CPAP) therapy, the number of microbubbles was reduced in one patient.Conclusions: These suggest that coexistence of PFO and OSA may associate with a greater risk of youth stroke. Decrease risk of stroke might occur if treating with CPAP in patients with OSA. [ABSTRACT FROM AUTHOR]

Abstract The optical transfer function (OTF) can be used to evaluate the performance of optical imaging systems comprehensively and objectively. However, current method of determining an OTF is based on analyzing the imaging process in the spatial domain and combining the Fourier transform. For this issue, replacing optical rays by waves, we studied the lens imaging process of a cosine-fringe pattern and obtained the OTF of the lens without using the Fourier transform. First of all, we analyzed the properties of the light waves emitted from the cosine-fringe pattern. Then according to the lens' parameters and the use conditions, the quantity and quality of the coherent waves collected and utilized by the lens were analyzed, and the parameters of the cosine-fringe pattern on the image plane were obtained. Finally, the method of investigation of OTFs for ideal lens and aberrant lens without using Fourier transform was obtained. [ABSTRACT FROM AUTHOR]

Immune reconstitution has improved outcomes for progressive multifocal leukoencephalopathy (PML), a potentially lethal brain disease caused by JC virus (JCV). However, an antiviral treatment to control JCV is needed when immune reconstitution is delayed or not possible. On the basis of in vitro efficacy, this study evaluated the effect of mefloquine on PML and factors that may predict PML outcomes. This 38-week, open-label, randomized, parallel-group, proof-of-concept study compared patients with PML who received standard of care (SOC) with those who received SOC plus mefloquine (250 mg for 3 days, then 250 mg weekly). Patients randomized to SOC could add mefloquine treatment at week 4. The primary endpoint was change from baseline to weeks 4 and 8 in JCV DNA copy number (load) in cerebrospinal fluid (CSF). Exploratory analyses evaluated factors that might correlate with clinical outcome. The majority of enrolled patients were HIV positive. Preplanned interim data analyses suggested that the study was unlikely to successfully demonstrate a significant difference between groups; therefore, the study was terminated prematurely. There was no significant difference between groups in CSF JCV DNA loads or clinical/MRI findings. Decrease in CSF JCV DNA load from baseline to week 4 was associated with a better clinical outcome at 16 weeks, as measured by Karnofsky scores. This study found no evidence of anti-JCV activity by mefloquine. An early decrease of CSF JCV DNA load appears to be associated with a better clinical outcome. [ABSTRACT FROM AUTHOR]

Microwave guiding along double parallel lines of femtosecond-laser-generated plasma filament has been demonstrated over a distance of about 8 cm in air, corresponding to a maximum microwave signal intensity enhancement more than sixfold the free-space propagation. It is shown that the operating frequency and the line electric width influence the propagation coefficient of microwaves propagating along this transmission line. Based on channeling microwaves along this line and by measuring and comparing the propagated microwave signals, the basic parameters of laser-generated plasma filament, namely, its electron density and conductivity, are obtained. [ABSTRACT FROM AUTHOR]

We report paleomagnetic results from the Late Carboniferous-Late Permian strata in eastern Tibet (China), and aim to clarify the tectonic and paleogeographic evolution of the northern Qiangtang-Qamdo block, which is the key to the study of plate boundary between the Gondwanaland and the Eurasia during the late Paleozoic. Two hundred and nineteen samples-including limestone, muddy siltstone, basalt, lava, and tuff-were collected at 24 sites in the Upper Carboniferous and Middle-Upper Permian successions. A systematic study of rock magnetism and paleomagnetism yields three reliable paleomagnetic pole positions. Both hematite and magnetite occurred in the Late Carboniferous limestone samples. The demagnetization curve shows a characteristic double-component, with the remanent magnetization (ChRM) exhibiting a positive polarity (negative inclination). In the Late Permian limestone, tuff, and basalt, magnetic information were recorded primarily in magnetite, although a small fraction of them was found in hematite in basalt. The demagnetization curve illustrates a double or single component, with the ChRM showing a negative polarity (positive inclination), which has passed the classic fold test successfully. The single polarity features of the ChRM directions of the Late Carboniferous and Middle-Late Permian rocks are respectively related to the Kiaman positive and reversed polarities under the stratigraphic coordinates. This, in turn, indicates that both ChRMs directions represent the original remanence directions. By comparison with the previously published paleomagnetic results from the late Paleozoic rocks in the northern Qiangtang Range, we suggest that: (1) Qamdo and northern Qiangtang block were independent of each other during the Late Carboniferous to the Early Permian periods. The north Lancangjiang ocean basin between the two blocks may have closed before the Middle Permian and been involved in the continent-continent collision stage in the Late Permian-Early Triassic periods. (2) The northern Qiangtang-Qamdo Block paleogeographically was situated at low to intermediate latitudes in the Southern Hemisphere in the Late Carboniferous-Late Permian periods, and began to displace northward in the Early Triassic, with an amount of more than 5000 km northward transport from its current location. [ABSTRACT FROM AUTHOR]

Tectonic evolution of the Tethys and the boundary between the Gondwanaland and the Eurasia during the Carboniferous and Permian remain hotly debated. Qiangtang region in the Qinghai-Tibet Plateau may be a key place to study these problems. A paleomagnetic study was conducted on the Late Paleozoic rocks in the northern Qiangtang region (33.7°N, 86.7°W), Tibet. Two sites (21 samples) in the Upper Carboniferous, eleven sites (101 samples) in the Permian, and two sites (16 samples) in the Lower Triassic were investigated. The rock magnetic data revealed hematite and magnetite as the main magnetic carriers. In stepwise thermal demagnetization and/or combined alternating field (AC) demagnetization, two characteristic components in the majority of the samples were identified as (1) the Low-temperature Component (LTC), characterized by northerly declination and moderate to steep inclination, corresponding to a pole position overlay with the present North Pole. A minority of the samples present single component, and their directions are the same as (2) the High-temperature Component (HTC) of double components. The combined single-component and HTC data of the Permian can pass the R-test at 95% level and the F-test at 99% level, as well as the BC-test. The pole position from the Late Carboniferous is at 31.8°S, 45.7°E with dp=2.1, dm=3.9, that from the Early and Middle (Late) Permian is at 31.7°S, 46.8°E with dp=9.2, dm=16.9 (34.4°N, 54.1°E with dp=6.9, dm=12.5) respectively, and that from the Early Triassic is at 16.9°S, 22.5°E with dp=4.9, dm=9.2. These pole positions are different from the other poles for the Qiangtang Block, which suggests the single-component and HTC directions are probably a primary magnetization and the northern Qiangtang Block was paleogeographically situated at low latitudes in the Northern Hemisphere in the Late Paleozoic. [ABSTRACT FROM AUTHOR]

In the Dabudaer region of the Tianshuihai Massif (Xinjiang, Northwest China), metavolcanic rocks within the mainly meta-sedimentary Bulunkuoler Group are basalt, basaltic andesite, and rhyolite. In situ zircon U-Pb LA-ICP-MS dating on rhyolite magmatic zircons yielded an age of 2481±14 Ma, interpreted as the eruption age of the Bulunkuoler Group volcanic rocks. The basalt and basaltic andesite are low-Al tholeiite series and the rhyolite is low-Al calc-alkaline series. All of rocks are characterized by enrichment of LREE and LILE (Rb, Th and Ba), depletion of P, Nb, Ta and Ti, and absence of Eu anomalies. The ε( t) of basalts ranges from 3.14 to 4.88 indicating a depleted mantle source. The trace element signatures show that these magmas experienced intense crustal contamination during their ascent. Direct evidence for crustal contamination is the xenocrystic zircons in the ryholite, with ages back to ca. 3300 Ma. The primitive-mantle normalized and Zr/Y-Zr diagrams for the basic volcanic rocks show that they formed in an intra-continental tectonic setting. Combined with the previous studies and compared with North China Craton Neoarchean basic volcanic rocks, it is supposed that the Bulunkuoler Group volcanic rocks reflect the Palaeoproterozoic mantle magma underplating and interaction with felsic crust. [ABSTRACT FROM AUTHOR]

Abstract: An experimental study was performed to measure the heat transfer coefficient distributions on a flat blade model under rotating operating conditions. A steady-state thermochromic liquid crystal technique was employed to measure the surface temperature, and all the signals from the rotating reference frame were collected by the telemetering instrument via a wireless connection. Both air and CO2 were used as coolant. Results show that the rotational effect has a significant influence on the heat transfer coefficient distributions. The profiles of hg /h 0, which is the ratio of heat transfer coefficient with film cooling to that without film cooling, deflect towards the high-radius locations on both the pressure surface and suction surface as the rotation number (Rt) increases, and the deflective tendency is more evident on the suction surface. The variations in mainstream Reynolds number (ReD ) and blowing ratio (M) present different distributions of hg /h 0 on the pressure and suction surfaces, respectively. Furthermore, the coolant used for CO2 injection is prone to result in lower heat transfer coefficients. [Copyright &y& Elsevier]

The Optical Transfer Function (OTF) is an important part of modern optics and is very useful for optical system design and evaluation. A non-Fourier transform OTF method has been recently proposed. It formulates the OTF based on the propagation of light in the frequency domain, combining the intuitiveness of geometrical optics and the accuracy of wave optics. To advance the non-Fourier transform OTF method, in this paper, we first applied it to a single convex lens and analyzed the influence of the optical pupil function on interference pairs to reveal the mechanism of how aberration affects the non-Fourier transform OTF. It was found that the aperture of the lens affects the utilization efficiency of the interference pair, and the aberration of the lens affects the utilization quality of the interference pair. Then we derived the generalized pupil function based on a two-lens system in applying this new non-Fourier transform OTF method to the analysis of complex optical systems. [ABSTRACT FROM AUTHOR]

The eigenstate of the Optical Transfer Function (OTF) theory is cosine fringe. In the non-Fourier transform OTF theory, the emission field of the cosine fringe is decomposed into an ensemble of interference pairs. In this paper, we use the interference theory of light to study the parameters of the two light beams of the interference pair. Afterward, we discuss the reflection coefficient of the cosine fringe and obtain the conclusion that the cosine fringe is a complex number. In addition, we analyze the interaction which is between illumination light and cosine fringe to obtain the state of the surface wave and its emission field, which reveals the mechanism of cosine fringe emission interference pairs. Furthermore, by comparing the interaction between illumination light and cosine fringe with communication modulation theory, we confirm that the principle of cosine fringe emission interference pairs is the same as that of Double-sideband suppressed-carrier. Finally, the optical imaging is analyzed by using the concept of photon ensemble, and come to the conclusion that ideal imaging does not exist. The work of this paper not only provides a basis for the non-Fourier transform OTF theory, but also contributes the illumination design of optical imaging systems. [ABSTRACT FROM AUTHOR]