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Based on the drilling results of the Taishen-1 well in the Sanhu area in the Qaidam Basin, the study proposed new findings on the conditions of source rock, reservoir, and overlaying strata, as well as accumulation characteristics for biogenic gas. Further, the controlling factors of biogenic gas accumulation as well as two favorable zones for exploration were identified based on the comparison of drilling results and geological findings in adjacent areas. The result of the study showed that: (1) the biogenic gas source rock in the Sanhu area is lacustrine dark mudstone, and the LLTOC (lower limit of total organic carbon) in Q1+2 (the Qigequan Formation) and N (the Neogene) is 0.25% and 0.40%; (2) the ‘self-generation and self-storage’ source-reservoir combination developed across all the formations due to the absence of faults and the development of mudstone; (3) the controlling factors of gas accumulation in the studied area include the limit of burial depth, the methane yield, and climate conditions. The failure of the Taishen-1 well owes to the fact that the gas generated failed to support the demand for gas accumulation; (4) influenced by the southward movement of gas-containing groundwater from the high potential area in the north, the biogenic gas reservoirs are distributed in the northern slope and the central sag of the Sanhu depression, and the lower limit of exploration depth of the biogenic gas reservoirs is about 2119 m; (5) two favorable zones were selected for natural gas exploration: the Upper Tertiary thermogenic gas-bearing Yahu-Sebei area and the biogenic gas-bearing Tainan-Sebei area.

Infectious diseases have a devastating impact on individual health and social development. Different external environmental factors will affect the scale and the speed of disease outbreaks, such as sanitary conditions and policy interventions. In this paper, we attempt to establish a dual-system susceptible-infectious-quarantine-recovered model with different environmental impacts to explore it. For the deterministic model, we calculate the basic reproduction number, simultaneously, and investigate the local asymptotic stability of the disease-free equilibrium and the endemic equilibrium. Numerical simulations and theoretical analyses verify the conclusion of this paper. It is a surprise that there is a great probability of finding a quarantine inflection point, which can effectively control the scale of infection outbreak when two different systems of infection rate and recovery rate are determined.

Bending modulus is a key parameter to characterize the stiffness of materials. Commonly, it is believed that the bending modulus is closely related to the thickness as described by the thin plate theory. However, the thin plate theory fails in multilayer van der Waals materials like multilayer graphene, suggesting a more complex relationship between the bending modulus and thickness. Here, rippled graphene structures containing non-hexagonal carbon rings with different thicknesses are constructed to study the thickness-dependent bending modulus by the first-principles calculations. It is found that the bending modulus of rippled graphene depends on several factors, such as geometry, bending curvature, and thickness. Particularly, for the egg-tray graphene structures with similar structural pattern and bending curvature, i.e., eliminating the effects of structural pattern and bending curvature, the bending modulus could show a linear relationship to the thickness. Moreover, this linear relationship is very robust even in the case of changing the thickness through heteroatom doping.

A Q-switched Er:YAG solid-state laser at 1645 nm based on black phosphorus (BP) saturable absorbers (SAs) was demonstrated firstly to our knowledge. The BP-SA was fabricated by drop-casting BP nanoplatelets dispersion on a YAG substrate and corresponding saturable absorption properties were characterized at 1.6 μm. By employing as-prepared BP-SAs, stable Q-switched laser operations were achieved with a pulse width of 2.8 μs and a repetition rate of 34 kHz, corresponding to the average output power of 0.33 W. The results verify that BP-SAs have great potential for pulsed 1.6 μm lasers.

A novel nickel–cobalt (NiCo)-layered double hydroxide (LDH) saturable absorber (SA) was fabricated by the liquid-phase exfoliation method and applied as the laser modulator for the first time. We successfully investigated the laser modulation performance of the NiCo-LDH SA at 2 µm with a passively Q-switched (PQS) Tm:YAG ceramic laser. The narrowest pulse width of 322.6 ns was obtained, corresponding to a pulse repetition frequency of 119.3 kHz and a single pulse energy of 2.10 µJ. As far as we know, this is the shortest pulse width of PQS Tm:YAG crystal and ceramic lasers with two-dimensional materials saturable absorber. The results show that NiCo-LDH SA is a promising candidate for the application of laser modulators at 2 µm.

Nickel-vanadium (NiV)-layered double hydroxide (LDH) was fabricated into a novel saturable absorber (SA) by the liquid phase exfoliation method and utilized as the laser modulator for the first time, to our best knowledge. We investigated a passive Q -switched Tm:YAG ceramic laser at 2 µm with the NiV-LDH SA. Under an absorbed pump power of 7.2 W, the shortest pulse width of 398 ns was obtained with an average output power of 263 mW and a pulse repetition frequency of 101.8 kHz, corresponding to a single pulse energy at 2.30 µJ. The results indicate that the NiV-LDH SA has great research potential in the field of laser modulation.

We demonstrate a narrow-linewidth linearly polarized 1645 nm Er:YAG laser, directly diode-pumped by a fiber-coupled continuous-wave laser diode at 1532 nm. Passive Q-switching is realized by a few-layer graphene saturable absorber. A maximum polarized average output power of 3.13 W is achieved at 23.28 W incident pump power. A pulse energy of as much as 58.8 μJ and pulse width of 4.21 μs are yielded at a 53.2 kHz pulse repetition rate. The spectrum and linewidth of the output beams are measured to be 1645.34 and 0.05 nm, respectively. This laser can be useful in the detection of atmosphere pollutants.

We demonstrate a potassium titanyl phosphate-based optical parametric oscillator (OPO) emitting at 1729 nm. A maximum output power of 1.56 W at 1729.4 nm is obtained with an original fundamental laser power of 5.48 W. The pulse with a pulse duration of 11.22 ns exceeds 3 mJ at a 500 Hz repetition rate. To our knowledge this is the highest energy output of an OPO laser emitting around 1.73 \mu m operating at a 100 Hz order of magnitude. This laser is primarily used for bond-selective imaging of deep tissue, a promising way for diagnosing vulnerable plaques in live patients.

Type division and controlling factor analysis of 3rd-order sequence are of practical significance to tectonic analysis, sedimentary environment identification, and other geological researches. Based on the comprehensive analysis of carbon and oxygen isotope trends, paleobathymetry and spectral-frequency of representative well logs, 3rd-order sequences can be divided into 3 types: (a) global sea level (GSL) sequence mainly controlled by GSL change; (b) tectonic sequence mainly controlled by regional tectonic activity; and (c) composite sequence jointly controlled by GSL change and regional tectonic activity. This study aims to identify the controlling factors of 3rd-order sequences and to illustrate a new method for classification of 3rd-order sequences of the middle Permian strata in the Sichuan Basin, China. The middle Permian strata in the Sichuan Basin consist of 3 basin-contrastive 3rd-order sequences, i.e., PSQ1, PSQ2 and PSQ3. Of these, PSQ1 is a GSL sequence while PSQ2 and PSQ3 are composite sequences. The results suggest that the depositional environment was stable during the deposition of PSQ1, but was activated by tectonic activity during the deposition of the middle Permian Maokou Formation.

The hydrocarbon exploration is presently going on well in the Bohai Bay Basin, where several coal-derived gas fields have been found in the Upper Palaeozoic. However, no significant breakthrough has been made in the exploration of Eastern Linqing Depression, which is located in the southwest of the Bohai Bay Basin. To improve the gas exploration efficiency, this study employed the petroleum system theory to analyze the accumulation elements and processes of coal-derived gas of Upper Palaeozoic in this area, and further summarized the natural gas accumulation model. Results showed that the source rocks of Upper Palaeozoic in Eastern Linqing Depression mainly consist of coal-measure strata of Benxi-Taiyuan Formations of Carboniferous, as well as Shanxi Formation and the Lower Shihezi Formation of Permian. Reservoirs are widely distributed from the bottom to the top, mainly consisting of carbonate rocks and sandstones. The carbonate rock reservoirs include the weathering crust of Ordovician and the dolomite within Ordovician, while sandstone reservoirs include the distributary channel sand bodies of delta plain and the meandering river channel sand bodies in Upper Palaeozoic, as well as sandstones of river and lacustrine in Mesozoic and Cenozoic. The whole region is covered by the semideep-deep lacustrine mudstone of Sha 3 member (Es3) of Palaeogene, which constitutes the regional cap rock in presence of many other localized cap rocks. There are four source-reservoir-cap assemblages including Upper Palaeozoic-generating and Mesozoic-preserving assemblage, Upper Palaeozoic-generating and Cenozoic-preserving assemblage, Upper Palaeozoic-generating and Upper Palaeozoic-preserving assemblage and Upper Palaeozoic-generating and Lower Palaeozoic-preserving assemblage. The source rock, reservoir and cap rocks match well in time and space. Tectonic evolution controlled the thermal evolution of the Upper Palaeozoic coal-measure source rocks, which experienced five hydrocarbon generation stages. Hydrocarbon generated from the coal strata of Upper Palaeozoic migrated to the surrounding traps through migration pathways consisting primarily of faults, cracks and unconformities, among which faults and unconformities played a major role. Multiple types of traps, mainly structural traps, were formed by the intense tectonic movements that historically occurred in this area. The trap formation stages match well with the hydrocarbon generation stages. By analyzing the accumulation conditions of coal-derived gas of Upper Palaeozoic, we identified four accumulation models and further predicted the favorable hydrocarbon accumulation zone in the study area.

We report high-energy linearly polarized operation of an Er:YAG laser at 1617 nm, resonantly pumped by quasi-continuous-wave 1470-nm laser diodes. A U-shape resonator incorporating two 0.25 at.% Er:YAG rods and an acousto-optic Q-switch was employed. Polarized output with pulse energy of 20.5 mJ and pulse width of 52 ns at a 50 Hz repetition rate was obtained. At the maximum output energy, the output beam quality M 2 was approximately 1.02 and 1.03 in horizontal and vertical directions, respectively. To the best of our knowledge, this polarized pulse energy is the highest ever reported for a directly diode-pumped Q-switched Er:YAG laser operating at 1617 nm.

A series of fluorinated pyrazoline derivatives were synthesized by the reaction of fluorinated chalcone with hydrazine ArNHNH2 (Ar=4-BrC6F4, 4-ClC6H4, C6H5, 4-CH3C6H4 and 4-CH3OC6H4). The structures of all these compounds were fully supported by their spectroscopic data and one of products was further confirmed by X-ray single crystal diffraction analysis. The capability of fluorinated triaryl-2-pyrazolines to detect metal cations was investigated, by monitoring changes in their fluorescence spectra in the presence of Cd2+, Co2+, Cu2+, Mn2+, Ni2+ and Zn2+.

An efficient laser diode end-pumped continuous-wave (CW) and AO Q-switched laser of Nd:LiLuF4 crystal with dual central wavelengths of 1053.1 and 1054.7 nm is reported for the first time. The maximum CW output power of 6.22 W was obtained at absorbed pump power of ∼14.6 W with the output transmission of 2%. The optical conversion efficiency is ∼43%, corresponding to a slope efficiency of about 48% with respect to the absorbed pump. For the Q-switched operation, the shortest pulse width of 17 ns was obtained at the pulse repetition frequency (PRF) of 0.5 kHz, resulting in a pulse energy of 2.24 mJ and peak power of 131.8 kW.

Diode end-pumped continuous-wave and passively Q-switched Nd:Lu x(x = 0.5) Y 1 − x VO 4 mixed crystal lasers were demonstrated. At the pump power of 12.6 W, the maximum output power of 6.7 W around 1066.5 nm was obtained with the output transmission of 27%. The optical conversion efficiency is 53.2%, corresponding to a slope efficiency of 55.8%. For pulsed operation, the shortest pulse width attained was 8.6 ns, with the pulse repetition frequency of 99 kHz, and the single pulse energy and the peak power were estimated to be 25.5 μJ and 2.96 kW, respectively.

Diode end-pumped continuous wave (CW) and passively Q-switched (PQS) laser performances of the mixed Nd:Gd0.33Lu0.33Y0.33VO4 crystal are investigated for the first time. At the pump power of 9 W, the highest output power is 3.66 W, with an optical conversion efficiency of 40.7% and a slope efficiency of 43.6%. For pulsed operation, the minimum pulse width of 9.2 ns with Cr4+:YAG as saturable absorber is attained with the repetition rate of 81.8 kHz, and the single pulse energy and peak power are estimated to be 9.78 J and 1.06 kW, respectively.

Resonantly gain-switched by a 1.9-μm Tm:YLF crystal laser, over 11 W ~ 2.1-μm laser output has been achieved from a Ho:LuAG rod laser with a slop efficiency of 83% with respect to absorbed pump power. The high quantum efficiency (~ 92%) was attributed to the compact cavity configuration, excellent mode overlap between the pump and laser beam, and efficient crystal cooling. Near the highest output level, the laser wavelength was centered at 2130 and 2101 nm, with the T = 8% and T = 20% output couplers, respectively. At 10-W power level, the laser beam quality was measured to be M2 ~ 1.02. The narrowest pulse width achieved was 20 ns and maximum pulse energy was over 4 mJ (2 kHz).

A new type host of germanate glass (GeO2− BaO−BaF2−Ga2O3−La2O3) codoped with Tm2O3 has been investigated for application as laser material. It possesses a large emission cross section with the value of 9.3×10−21 cm2 at 1.8 μm. Judd-Ofelt intensity parameters and radiative transition probability are calculated and analyzed by Judd-Ofelt theory and absorption spectra. The infrared emission spectra at 1.8 μm have been obtained by using a 794 nm laser diode as excitation resource. The emission intensity ratio of 1.8 (3F4→3H6) to 1.47 μm (3H4→3F4) increases, while the experimental lifetime of the Tm3+:3H4 level decreases by increasing Tm2O3 concentration, which is attributed to the presence of a cross relaxation process. The most intensive emission at 1.8 μm is achieved from the germanate glass with the concentration of Tm2O3 reaches 1.0 wt%. The extended overlap integral method is used to calculate the microparameter of the energy transfer and the critical distance, which are derived to better understand the energy transfer process of thulium ions in the germanate glass responsible for emission at 1.8 μm.

Lasers from Ho:YAG ceramic were reported in this paper. The Ho:YAG ceramic slab was end-pumped by a Tm:YLF laser whose central wavelength was 1.91 μm. At room temperature, with doping concentrations of 1 at.% Ho:YAG ceramic slab, continuous wave output power of 1.2 W at 2.09 μm was obtained under the absorbed pump power of 5 W, corresponding to a slope efficiency of 42.6% and a conversion efficiency of 24%.

Laser characteristics of a novel mixed laser crystal Nd:Lu0.15Y0.85VO4 was investigated. It is attractive for Q-switching with high repetition rate and short pulse width due to its suitable stimulated emission cross-section and short upper level lifetime. Continuous wave (CW) output power of 8.18 W was obtained at the pump power of 18.9 W, corresponding to the optical conversion efficiency of 43.3% and the slope efficiency of 47%. In the passive Q-switching operation, the minimum pulse width attained was 7.8 ns, with the pulse repetition frequency of 23.2 kHz, with the single pulse energy and peak power estimated to be 94.8 μJ and 12.2 kW, respectively.

We demonstrate a passively Q-switched Ho,Pr:LiLuF4 laser at 2.95 μm using a WS2 saturable absorber (SA). A shortest pulse width of 654 ns was achieved with an average output power of 82 mW and the repetition rate of 90.4 kHz at T = 2%. Our result reveals that WS2 -SAs have great potential to be the modulator in mid-IR wavelength range.

A continuous-wave (CW) and actively Q-switched Nd:Lux(x=0.15) Y 1-xVO4 laser was demonstrated for the first time. The maximum CW output power of 9.92 W was obtained, corresponding to an optical conversion efficiency of 52.5% and a slope efficiency of 56.1%. For actively Q-switched operation, a 10.4-ns pulse was attained with the repetition frequency of 10 kHz. Under the same conditions, the pulse energy and the peak power were estimated to be 0.6 mJ and 57.9 kW, respectively.

We describe high-energy Erbium-doped yttrium aluminum garnet (Er:YAG) lasers operating at 1617 nm, resonantly pumped using 1532 nm fiber-coupled laser diodes. A maximum continuous wave output power of 4.3 W at 1617 nm was achieved with an output coupler of 20% transmission under incident pump power of 29.7 W, resulting in an optical conversion of 14% with respect to the incident pump power. In Q-switched operation, the pulse energy of 11.8 mJ at 100 Hz pulse repetition frequency and 81 ns pulse duration was obtained. This energy is the highest pulse energy reported for a directly diode-pumped Q-switched Er:YAG laser operating at 1617 nm.

In order to obtain laser output around 1.6um with high power and high overall efficiency, 1532nm narrow-band LD directly pumped Er:YAG laser is investigated. Performance of laser output with distinct doping concentration of gain medium is recorded and compared. Using 0.25% doped, 4cm long Er:YAG rod as the gain medium, we get over 10W laser output with about 31W incident pump power. The optical efficiency is about 33% and the slope efficiency with respect to the absorbed pump power is as high as 83%. Up to now, this is the most efficient Er:YAG laser pumped in this manner with traditional rod or slab geometry.

CNC manufacturing online monitoring technology is a significant method to improve the processing quality and achieve an important part of intelligent processing. Based on OpenGL 3D graphics technology, a Computer Numerical Control (CNC ) Laser Manufacturing 3D model is established; base d on the model and the powerful ability of OpenGL, a CNC manufacturing on-line monitoring system is developed so as to achieve the ability of CNC remote real-time online monitoring in different working locations. Remote real-time online monitoring of different position of the CNC is realized. The online monitoring scope of the CNC is enlarged, with more flexibility to meet the demands of practical application, meanwhile the cost of hardware investment is greatly reduced. Keywords : OpenGL, three-dimensional modeling, online monitoring 1. INTRODUCTION OpenGL is a graphical environment developed by the Silicon Graphics (SGI) [1] , which is used for its graphics workstations independent of the windowing system, operating systems and hardware environment. It can run in the Windows, Mac OS, UNIX and other operating systems

Nine important vegetables were collected from northern Chinese wholesale markets and analyzed for polycyclic aromatic hydrocarbon (PAH) contents. Anthracene, flupranthene, benzo(a)anthracene and benzo(a)pyrene were determined. The contents of the four PAH congeners were at the same level with the mean concentrations 6.46, 4.05, 3.33, 4.51 µg kg−1 for fresh weight for anthracene, flupranthene, benzo(a)anthracene and benzo(a)pyrene, respectively. However, leafy and stem vegetables had higher PAH content than root and fruit vegetables. Peels of the root and fruit vegetables had higher PAH concentrations than their cores. Human exposure to PAHs by consumption of these vegetables is estimated, by using typical northern Chinese intake rates, although the study was not designed to be statistically representative for the China as a whole.

An efficient, directly diode-pumped Er:YAG laser at 1617 nm was demonstrated. A folding mirror with high reflectivity for the s-polarized light at the laser wavelength was used to achieve a linearly polarized laser. A maximum continuous-wave output power of 7.73 W was yielded under incident pump power of 50.57 W, and the optical conversion efficiency with respect to incident pump power was ∼15.28%, which was the highest optical conversion efficiency with directly diode-pumped Er:YAG lasers up to now; in Q-switched operation, the maximum pulse energy of 7.82 mJ was generated with pulse duration of about 80 ns at a pulse repetition frequency of 500 Hz.

We report a polarized, narrow-linewidth Er:YAG laser operating at 1645 nm, in-band pumped by a continuous-wave (CW), narrowband 1532 nm fiber-coupled laser diode (LD). A maximum polarized continuous wave output power of 8.45 W was obtained, resulting in an optical conversion efficiency of 56% with respect to the absorbed pump power. The central wavelength was measured to be 1645.45 nm, with a full width at half-maximum of 0.13 nm. For Q-switched operation, pulse energy of 12 mJ at 100 Hz pulse repetition frequency and 95 ns pulse duration was yielded. To the best of our knowledge, this polarized pulse energy is the highest energy reported for a Q-switched Er:YAG laser pumped by a CW LD.

We report, for the first time to our knowledge, an acousto-optic Q-switched Er3+:Yb3+:YVO4 laser end-pumped by a fiber-coupled diode laser at 976 nm. A maximum continuous wave output power of 230 mW at 1602.6 nm was obtained with an output coupler of 2% transmission under an absorbed pump power of 7.2 W. In Q-switched operation, a wide range of repetition rates from 500 Hz to 50 kHz was demonstrated. 0.19 mJ maximum pulse energy with 130 ns pulse duration was obtained at a repetition rate of 500 Hz. A reduced storage time of the upper laser level was discovered, which was suggested to be a result of up-conversion loss.

We first report an all-solid-state tunable mid-infrared singly resonant optical parametric oscillator based on a 1532 nm laser diode resonantly pumped, Q-switched 1.645 μm Er:YAG laser. An MgO-doped periodically poled lithium niobate was used as the nonlinear material. At the pulse repetition frequency of 2 KHz, a maximum overall average output power of 0.95 W with pump power of 2.8 W was achieved, corresponding to a conversion efficiency of 34% and a slope efficiency of 38%. The temperature tuning was performed giving signal and idler ranges of 2.67 to 2.71 μm and 4.18 to 4.31 μm, respectively.

Energy transfer upconversion induced thermal effects are mainly responsible for the low efficiency of laser diode pumped Er:YAG lasers. The current work adopts Er:YAG rods with 0.25% Er(3+) doping concentration, instead of the commonly used rods with 0.5% Er(3+) doping concentration. Results show that the thermal effect is greatly alleviated. A continuous-wave output of 10.2 W is obtained using 31 W incident pump power. Optical-optical efficiency is approximately 33%. Slope efficiency, with respect to the absorbed pump power, is as high as 83%, which is close to the quantum efficiency. In a Q-switched operation, 7 mJ pulses with a pulse width of ~65 ns are obtained at 100 Hz PRF.

In order to conveniently and precisely estimate the spot size of laser modes in continuously single-end-pumped solid-state lasers, a ray matrix for the thermal-induced lenslike medium with exponential heat distribution along the axial direction is, for the first time to our best knowledge, derived under assumptions of only radial heat flow and uniform pump spot size. An equivalent optical model is also developed and especially modified for a lenslike gain medium in a continuously single-end-pumped solid-state laser. The result is verified by discussing how it fits the practical cases much better than the previous simplified model and by numerical simulation in a practice problem. This work is especially important in cases with a relatively long gain medium, which has been used more and more frequently in recent years.

We demonstrated a diode-pumped continuous wave and passively Q-switched Nd:Lu(x)Y(1-x)VO4 laser at 1.34 μm with V3+:YAG as the saturable absorber. The crystal Nd:Lu(x)Y(1-x)VO4 with equal ionic ratio (x = 0.5) shows better laser performance. The maximum continuous wave output power of 1.45 W was obtained with the optical efficiency of 20.1% and the slope efficiency of 24.5%. For the pulsed operation, the minimum pulse width achieved was 42 ns with the pulse repetition frequency of 142 kHz, and the single pulse energy and the peak power were estimated to be 6.62 μJ and 157.6 W, respectively.

Characteristics of Tm:YAG ceramic for high efficient 2-μm lasers are analyzed. Efficient diode end-pumped continuous-wave and Q-switched Tm:YAG ceramic lasers are demonstrated. At the absorbed pump power of 53.2W, the maximum continuous wave (cw) output power of 17.2 W around 2016 nm was obtained with the output transmission of 5%. The optical conversion efficiency is 32.3%, corresponding to a slope efficiency of 36.5%. For Q-switched operation, the shortest width of 69 ns was achieved with the pulse repetition frequency of 500 Hz and single pulse energy of 20.4 mJ, which indicates excellent energy storage capability of the Tm:YAG ceramic.