八家子林业局林场实行撤并重组的探讨

根据森工企业森林资源现状和实行限额采伐的现实 ,对林场规模、布局进行了研究分析。目前 ,林场只有实行撤并重组、科学规划、讲求效益 ,才能推进森工企业体制改革和实现林业可持续发展。

Schrdinger Cat States in a Mesoscopic Josephson Junction

To study the nonclassical effects of the mesoscopic Josephson junction in the presence of a nonclassical microwave, the mesoscopic Josephson junction and the field were both treated quantum mechanically, and the external field approximation was used. It is shown that if the external field is in the coherent state and the state of the junction is initially prepared in the vacuum state, the state of the junction can evolve into a quantum superposition of two coherent states. The Schrdinger cat states can be produced in a mesoscopic Josephson junction.

Thermal Entanglement of a Two-Qubit XXZ Heisenberg Chain with Dzialoshinski-Moriya Interaction

The effect of DziaJoshinski-Moriya （DM） interaction on thermal entanglement of a two-qubit XXZ spin chain in a homogenous magnetic field is investigated. It is found that the DM interaction can enhance thermal entanglement. When D is large enough, the entanglement can exist for larger temperatures and strong magnetic field.

Residential Energy Consumption and Associated Carbon Emission in Forest Rural Area in China: A Case Study in Weichang County

Rural energy consumption in China has increased dramatically in the last decades, and has become a significant contributor of carbon emissions. Yet there is limited data on energy consumption patterns and their evolution in forest rural areas of China. In order to bridge this gap, we report the findings of field surveys in forest villages in Weichang County as a case study of rural energy consumption in northern China. We found that the residential energy consumption per household is 3313 kgce yr^-1 （kilogram standard coal equivalent per year）, with energy content of 9.7×lO7 kJ yr^-1, including 1783 kgce yr^-1 from coal, 1386 kgce yr^-1 from fuel wood, 96 kgce yr^-1 from electricity, and 49 kgce yr^-1 from LPG. Per capita consumption is 909 kgce yr^-1 and its energy content is 2.7×lO7 kJ yr^-1. Due to a total energy utilization efficiency of 24.6%, all the consumed energy can only supply about 2.4×107 kJ yr^-1 of efficient energy content. Secondly, household energy consumption is partitioned into 2614 kgce yr^-1 for heating, 616 kgce yr^-1 for cooking, and 117 kgce yr^-1 for home appliances. Thirdly, the associated carbon emissions oer household are 2556 kzC yr^-1, includinz1022 kgC yr^-1 from unutilized fuel wood （90% of the total fuel wood）. The rest of emissions come from the use of electricity （212 kgC yr^-1, coal （13Ol kgC yr^-1 and LPG （21 kgC yr^-1. Fourthly, local climate, family size and household income have strong influences on rural residential energy consumption. Changes in storage and utilization practices of fuel can lead to the lO%-30% increase in the efficiency of fuel wood use, leading to reduced energy consumption by 924 kgce yr^-1 per household （27.9% reduction） and 9Ol kgC yr^-1 of carbon emissions （35-3% reduction）.

Thermal Entanglement of a Three-Qubit Heisenberg Chain with a Nonuniform Magnetic Field

The thermal entanglement of a three-qubit Heisenberg chain under a nonuniform magnetic field is studied. It is very interesting to note that the next nearest neighbor entanglement （NNNE） could be larger than the nearest neighbor entanglement （NNE）. We analyze the ground state entanglement, and give the conditions that NNNE is larger than NNE near zero temperature. Our results also show that the nonuniform field could induce the entanglement and improve the threshold temperature at certain parameter region.

Heisenberg Model in a Rotating Magnetic Field

We study the Hcisenberg moder under the influence of a rotating magnetic field. By using a time- dependent unitary transformation, the time evolution operator for the Schrodinger equation is obtained, which involves no chronological product. The spin vectors (mean values of the spin operators) are obtained as explicit functions of time in the most general case. A series of cyclic solutions are presented. The nonadiabatic geometric phases of these cyclic solutions are caleulated, and are expressed in terms of the solid angle subtended by the closed trace of thc total spin vector, as well as in terms of those of the individual spins.

Alterations of the Nitrogen Mineralization Rates in Soils of Forest Community Depending on the Ski Run Construction (Mount Uludag,Bursa,Turkey)

Since 194os, Mount Uludag （Bithynian Olympus） has been considered famous with winter sports center in Turkey. In addition, it is one of the rare places because of its plant diversity and is also one of the important plant areas of Turkey. The ski run constructions are rapidly increased in the past decades in the alpine and subalpine belts of the mountain. Rate of nitrogen mineralization and some properties of soft were investigated in the soils of the three ski runs and undisturbed neighborhood forest sites. These ski runs are at the upper part of the forest belt in the mountain. Abies bornmuelleriana forest community is the postclimax and very sensitive to destruetion. The rates of the nitrogen mineralization in the soils were determined in controlled conditions （60% water-holding capacity, 20℃）. Nitrification and nitrogen mineralization were in the ski run inside where the natural recovery started, increased compared with the outside of the ski runs. Waterholding capacity, organic carbon, and total nitrogen were decreased in the massive damaged ski run, and due to these changes, the rates of mineralization and nitrification were also decreased.

Effects of Different Spin-Spin Couplings and Magnetic Fields on Thermal Entanglement in Heisenberg XYZ Chain

The effects of spin-spin interaction on thermed entanglement of a two-qubit Heisenberg XYZ model with different inhomogeneous magnetic fields are investigated. It is shown that the entanglement is dependent on the spin-spin interaction and the inhomogeneous magnetic fields. The larger the Ji （i-axis spin-spin interaction）, the higher critical value the Bi （i-axis uniform magnetic field） has. Moreover, in the weak-field regime, the larger Ji corresponds to more entanglement, while in the strong-field regime, different Ji correspond to the same entanglement. In addition, it is found that with the increase of Ji, the concurrence can approach the maximum value more rapidly for the smaller Bi, and can reach a larger value for the smaller bi （i-axis nonuniform magnetic field）. So we can get more entanglement by increasing the spin-spin interaction Ji, or by decreasing the uniform magnetic field Bi and the nonuniform magnetic field hi.

Effects of Nonlinear Couplings on Entanglement in a Two-Qutrit Heisenberg XXX Chain under an Inhomogeneous Magnetic Field

This paper investigates the entanglement of a two-qutrit Heisenberg XXX chain with nonlinear couplings under an inhomogeneous magnetic field. By the concept of negativity, we find that the critical temperature increases with the increase of inhomogeneous magnetic field b. Our study indicates that for any ｜K｜ 〉 ｜J｜, or ｜K｜ 〈 ｜J｜ entanglement always exists for certain regions. We also find that at the critical point, the entanglement becomes a nonanalytic function of B and a quantum phase transition occurs.

Influence of Bipartite Qubit Coupling on Geometric Phase

The geometric phase of the bipartite Heisenberg spin-1/2 system with one spin driven by rotating magnetic field is investigated. It is found that in the one-site drive case, the intersubsystem coupling can be equivalent to a static quasi-magnetic field in the parameter space. This perspective has satisfactorily explained the irregular asymptote effect of geometric phase. We discuss the property of the two-site magnetic drive spin system and discover that a stationary state with no geometric phase shift is generated.

Entanglement and Teleportation via Thermally Entangled State of Anisotropic Heisenberg XYZ Chain with Inhomogeneous External Magnetic Field

In this paper we study the entanglement in a two-qubit spin in the XYZ model, and teleport a two-qubit entangled state using this spin chain in the condition of the thermal equilibrium as a quantum channel. We investigate the effects of the interaction of z-component Jz, the inhomogeneous magnetic field b, the anisotropy γ and the temperature T on the entanglement and fidelity. In order to characterize the quality of the teleported state, we research the average fidelity Fα. High average fidelity of the teleportation is obtained when the temperature is very low. Under some condition, we also find that when innomogeneity increases to a certain value, the average fidelity can exhibit a larger revival than that for less values of b.

The status and protection of the ecological environment in Heihe River water source district

This article discusses the status of the ecological environment in Heihe River water source district, and points out that the decline of the forest coverage, the degradation of the pasture and the shrinking back of the glacier, the increased soil erosion and other phenomena are the main ecological and environmental problems in this area. The main reason is the natural and man-made results. This article proposes the specific measures to protect the ecological environment in Heihe River water source district.

Entanglement of a Five-Qubit Heisenberg XX Chain in a Magnetic Field

We calculate the eigenvalues and eigenvectors of a five-qubit isotropic Heisenberg model in an external magnetic field, and give analytical results for the concurrence of two nearest-neighbor qubits. A magnetic field can eliminate degeneration and change the ground state of the system. Therefore increasing the value of the magnetic field can induce entanglement in a certain range both for the antiferromagnetic and ferromagnetic case.

Entanglement Resonance of End Spins in Different Spin Chains

The entanglement resonance in anisotropic spin-1/2 Heisenberg chains of different couplings is investigated when the nearest neighbor coupling is periodically modulated with external magnetic field. When the modulation frequency equals twice of the magnetic field, the entanglement resonance is larger than that at other modulation frequencies and decreases as the number of spins in the chain increases. When the modulation frequency equals the magnetic field, the entanglement resonance can be reduced to a quite low value by varying the coupling along z axis.

Entanglement in a two-spin (1/2,3/2) mixed-spin Heisenberg XX chain with an inhomogeneous external magnetic field

By using the concept of negativity, we investigate the thermal entanglement of a two-spin (1/2, 3/2) mixed-spin Heisenberg XX chain with an inhomogeneous external magnetic field. We obtain the analytical results of entanglement of this model. For the case of uniform magnetic field, we find that the critical temperature is higher than the results of the spin-1/2 chain and (1/2,1) mixed-spin chain. And by adjusting the nonuniform parameter b, one is able to obtain more entanglement at a higher temperature.

A significant carbon sink in temperate forests in Beijing: based on 20-year field measurements in three stands

Numerous efforts have been made to characterize forest carbon （C） cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stocks and fluxes in three per- manent temperate forest plots （birch, oak and pine forest） during 2011-2014, and calculated the changes of the components of the C cycle related to the measurements during 1992-1994 at Mr. Dongling, Beijing, China. Forest net primary production in birch, oak, and pine plots was 5.32, 4.53, and 6.73 Mg C ha-1 a-1, respectively. Corresponding net ecosystem production was 0.12, 0.43, and 3.53 Mg C ha-1 a-1. The C stocks and fluxes in 2011-2014 were significantly larger than those in 1992-1994 in which the biomass C densities in birch, oak, and pine plots increased from 50.0, 37.7, and 54.0 Mg C ha-1 in 1994 to 101.5, 77.3, and 110.9 Mg C ha a in 2014; soil organic C densities increased from 207.0, 239.1, and 231.7 Mg C ha-1 to 214.8, 241.7, and 238.4 Mg C ha-l; and soil heterotrophic respiration increased from 2.78, 3.49, and 1.81 Mg C ha-1 a-1 to 5.20, 4.10, and 3.20 Mg C ha-1 a-l. These results suggest that the mountainous temperate forest ecosystems in Beijing have served as a carbon sink in the last two decades. These observations of C stocks and fluxes provided field-based data for a long-term study of C cycling in temperate forest ecosystems.

Quantum Teleportation via Completely Anisotropic Heisenberg Chain in Inhomogeneous Magnetic Field

The quantum teleportation with the entangled thermai state is investigated based on the completely anisotropie Heisenberg chain in the presence of the externally inhomogeneous magnetic field. The effects of the anisotropy and magnetic field for the quantum fidelity are studied in detail The zero temperature limit and the features of the nonzero temperature for this nonclassical fdelity are obtained. We find that the quantum teleportation demands more stringent conditions than the therma/ entanglement of the resource by investigating the threshold temperature of the thermal concurrence and the criticai temperature of the maximai teleportation fidelity. The useful quantum teleportation should avoid the point of the phase transition of the system and the anisotropy of the chain and the external magnetic field can control the applicability of the resource in the quantum teleportation.