356 research outputs found
Evaluation of the Dynamic Characteristics of AZ91D Crankcase Covers and Boxes
Dynamic tests are performed on similarly structured crankcase covers and boxes made of AZ91D magnesium and A380 aluminum alloys. The real vibration and noise control effect of an AZ91D magnesium alloy is evaluated, based on the behavior of the integral frequency response function, which is derived from the measured surface vibrations of the crankcase cover under operating conditions. The results indicate that crankcase covers and boxes made of AZ91D magnesium and A380 aluminum alloys with the same geometry possess similar normal characteristics. Both materials are interchangeable. However, the stiffness of AZ91D crankcase covers and boxes is poor. It is also difficult to obtain good engineering vibration and noise effects in the real structure due to an AZ91D high damping capacity. At the same excitation and frequency response at different structure characteristics, the measurement analysis of time-domain response indicates that methods to strengthen the crankcase box stiffness, such as embedding a main bearing steel sleeve, is favorable for improving the dynamic characteristics of an AZ91D crankcase box.ΠΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΈΡΠΏΡΡΠ°Π½ΠΈΡ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΠΈ Π½Π° ΠΊΠ°ΡΡΠ΅ΡΠ½ΡΡ
ΠΊΡΡΡΠΊΠ°Ρ
ΠΈ ΠΏΠΎΠ΄Π΄ΠΎΠ½Π°Ρ
Π°Π½Π°Π»ΠΎΠ³ΠΈΡΠ½ΠΎΠΉ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΈ, ΠΈΠ·Π³ΠΎΡΠΎΠ²Π»Π΅Π½Π½ΡΡ
ΠΈΠ· ΠΌΠ°Π³Π½ΠΈΠ΅Π²ΠΎΠ³ΠΎ AZ91D ΠΈ Π°Π»ΡΠΌΠΈΠ½ΠΈΠ΅Π²ΠΎΠ³ΠΎ Π380 ΡΠΏΠ»Π°Π²ΠΎΠ². ΠΡΠ΅Π½Π΅Π½ ΡΡΡΠ΅ΠΊΡ ΠΎΡ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ ΠΌΠ°Π³Π½ΠΈΠ΅Π²ΠΎΠ³ΠΎ ΡΠΏΠ»Π°Π²Π° AZ91D Π΄Π»Ρ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ ΡΠ΅Π°Π»ΡΠ½ΠΎΠΉ Π²ΠΈΠ±ΡΠ°ΡΠΈΠΈ ΠΈ ΡΡΠΌΠ° Π½Π° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠ° ΠΈΠ½ΡΠ΅Π³ΡΠ°Π»ΡΠ½ΠΎΠΉ ΡΠ°ΡΡΠΎΡΠ½ΠΎΠΉ ΡΡΠ½ΠΊΡΠΈΠΈ ΠΎΡΠΊΠ»ΠΈΠΊΠ°, ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΠΎΠΉ ΠΏΠΎ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠ°ΠΌ ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΡ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠ½ΠΎΠΉ Π²ΠΈΠ±ΡΠ°ΡΠΈΠΈ ΠΊΠ°ΡΡΠ΅ΡΠ½ΠΎΠΉ ΠΊΡΡΡΠΊΠΈ Π² ΡΠ°Π±ΠΎΡΠ΅ΠΌ ΡΠ΅ΠΆΠΈΠΌΠ΅. Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΏΠΎΠΊΠ°Π·ΡΠ²Π°ΡΡ, ΡΡΠΎ ΠΊΠ°ΡΡΠ΅ΡΠ½ΡΠ΅ ΠΊΡΡΡΠΊΠΈ ΠΈ ΠΏΠΎΠ΄Π΄ΠΎΠ½Ρ, ΠΈΠ·Π³ΠΎΡΠΎΠ²Π»Π΅Π½Π½ΡΠ΅ ΠΈΠ· ΠΌΠ°Π³Π½ΠΈΠ΅Π²ΠΎΠ³ΠΎ AZ91D ΠΈ Π°Π»ΡΠΌΠΈΠ½ΠΈΠ΅Π²ΠΎΠ³ΠΎ Π380 ΡΠΏΠ»Π°Π²ΠΎΠ², Ρ ΠΎΠ΄ΠΈΠ½Π°ΠΊΠΎΠ²ΡΠΌΠΈ Π³Π΅ΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ ΠΈΠΌΠ΅ΡΡ Π°Π½Π°Π»ΠΎΠ³ΠΈΡΠ½ΡΠ΅ Π½ΠΎΡΠΌΠ°Π»ΡΠ½ΡΠ΅ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ. ΠΠ±Π° ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π° Π²Π·Π°ΠΈΠΌΠΎΠ·Π°ΠΌΠ΅Π½ΡΠ΅ΠΌΡ. ΠΠ΄Π½Π°ΠΊΠΎ ΠΊΠ°ΡΡΠ΅ΡΠ½Π°Ρ ΠΊΡΡΡΠΊΠ° ΠΈ ΠΏΠΎΠ΄Π΄ΠΎΠ½ ΠΈΠ· ΡΠΏΠ»Π°Π²Π° AZ91D ΠΎΠ±Π»Π°Π΄Π°ΡΡ Π½ΠΈΠ·ΠΊΠΎΠΉ ΠΆΠ΅ΡΡΠΊΠΎΡΡΡΡ. ΠΠΎΡΡΠΈΡΡ Π½ΠΎΡΠΌΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΡΠ΅Ρ
Π½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΡΠΎΠ²Π½Ρ Π²ΠΈΠ±ΡΠ°ΡΠΈΠΈ ΠΈ ΡΡΠΌΠ° Π² ΡΠ΅Π°Π»ΡΠ½ΠΎΠΉ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΈ ΡΠ°ΠΊΠΆΠ΅ Π·Π°ΡΡΡΠ΄Π½ΠΈΡΠ΅Π»ΡΠ½ΠΎ, ΠΏΠΎΡΠΊΠΎΠ»ΡΠΊΡ ΡΠΏΠ»Π°Π² AZ91D ΠΎΠ±Π»Π°Π΄Π°Π΅Ρ Π²ΡΡΠΎΠΊΠΎΠΉ Π΄Π΅ΠΌΠΏΡΠΈΡΡΡΡΠ΅ΠΉ ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΡΡ. ΠΡΠΈ ΠΎΠ΄ΠΈΠ½Π°ΠΊΠΎΠ²ΠΎΠΌ Π²ΠΎΠ·Π±ΡΠΆΠ΄Π΅Π½ΠΈΠΈ ΠΈ ΡΠ°ΡΡΠΎΡΠ½ΠΎΠΉ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠ΅ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠΈ Ρ ΡΠ°Π·Π»ΠΈΡΠ½ΡΠΌΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠ°ΠΌΠΈ Π°Π½Π°Π»ΠΈΠ· ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΡ Π²ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΠΉ ΠΎΠ±Π»Π°ΡΡΠΈ ΠΏΠΎΠΊΠ°Π·ΡΠ²Π°Π΅Ρ, ΡΡΠΎ ΠΌΠ΅ΡΠΎΠ΄Ρ ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΡ ΠΆΠ΅ΡΡΠΊΠΎΡΡΠΈ ΠΊΠ°ΡΡΠ΅ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΠ΄Π΄ΠΎΠ½Π°, Π½Π°ΠΏΡΠΈΠΌΠ΅Ρ Π²ΠΌΠΎΠ½ΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ Π³Π»Π°Π²Π½ΠΎΠ³ΠΎ ΡΡΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΠ΄ΡΠΈΠΏΠ½ΠΈΠΊΠ° ΡΠΊΠΎΠ»ΡΠΆΠ΅Π½ΠΈΡ, ΡΠΏΠΎΡΠΎΠ±ΡΡΠ²ΡΡΡ ΡΠ»ΡΡΡΠ΅Π½ΠΈΡ Π΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ ΠΊΠ°ΡΡΠ΅ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΠ΄Π΄ΠΎΠ½Π° ΠΈΠ· ΡΠΏΠ»Π°Π²Π° AZ91D
Mitigating ammonia emission from agriculture reduces PM2.5 pollution in the Hai River Basin in China
The Hai River Basin (HRB), one of the most populated areas in China, is experiencing high NH3 emissions, mostly from agricultural sources, and suffering from strongly enhanced PM2.5 concentrations in all urban areas. Further population growth and urbanization projected until 2030 may exacerbate this situation. Here, the NUFER (NUtrient flows in Food chains, Environment and Resources use) and GAINS (Greenhouse gas β Air pollution Interactions and Synergies) models have been coupled for the first time to understand possible changes of agricultural NH3 emission between 2012 and 2030 and their impacts on ambient PM2.5 concentrations, and to explore options to improve this situation. Results show that agricultural ammonia emissions in the HRB were 1179 kt NH3 in 2012, 45% of which was from the hotspots at or near conurbation areas, including Beijing-Tianjin, Tangshan-Qinhuangdao, Shijiazhuang-Baoding, Dezhou, Handan-Liaocheng, and Xinxiang. Without intervention, agricultural ammonia emissions will further increase by 33% by 2030. The impacts of several scenarios were tested with respect to air pollution. Compared to the business-as-usual scenario, a scenario of improved technology and management combined with human diet optimization could greatly reduce emission (by 60%), and lead to 22β43% and 9β24% decrease of the secondary inorganic aerosols and PM2.5 concentrations, respectively, in the hotspots of NH3 emissions. Our results further confirmed that ammonia control is needed for air pollution abatement strategies (SO2, NOx and primary PM reduction) to be effective in terms of PM2.5
Isotope effect in impure high T_c superconductors
The influence of various kinds of impurities on the isotope shift exponent
\alpha of high temperature superconductors has been studied. In these materials
the dopant impurities, like Sr in La_{2-x}Sr_xCuO_4, play different role and
usually occupy different sites than impurities like Zn, Fe, Ni {\it etc}
intentionally introduced into the system to study its superconducting
properties.
In the paper the in-plane and out-of-plane impurities present in layered
superconductors have been considered. They differently affect the
superconducting transition temperature T_c. The relative change of isotope
shift coefficient, however, is an universal function of T_c/T_{c0} (T_{c0}
reffers to impurity free system) {\it i.e.} for angle independent scattering
rate and density of states function it does not depend whether the change of
T_c is due to in- or out-of-plane impurities. The role of the anisotropic
impurity scattering in changing oxygen isotope coefficient of superconductors
with various symmetries of the order parameter is elucidated. The comparison of
the calculated and experimental dependence of \alpha/\alpha_0, where \alpha_0
is the clean system isotope shift coefficient, on T_c/T_{c0} is presented for a
number of cases studied.
The changes of \alpha calculated within stripe model of superconductivity in
copper oxides resonably well describe the data on
La_{1.8}Sr_{0.2}Cu_{1-x}(Fe,Ni)_xO_4, without any fitting parameters.Comment: 8 pages, 6 figures, Phys. Rev. B67 (2003) accepte
Transmissibility of non-linear output frequency response functions with application in detection and location of damage in MDOF structural systems
Transmissibility is a well-known linear system concept that has been widely applied in the diagnosis of damage in various engineering structural systems. However, in engineering practice, structural systems can behave non-linearly due to certain kinds of damage such as, e.g., breathing cracks. In the present study, the concept of transmissibility is extended to the non-linear case by introducing the Transmissibility of Non-linear Output Frequency Response Functions (NOFRFs). The NOFRFs are a concept recently proposed by the authors for the analysis of non-linear systems in the frequency domain. A NOFRF transmissibility-based technique is then developed for the detection and location of both linear and non-linear damage in MDOF structural systems. Numerical simulation results verify the effectiveness of the new technique. Experimental studies on a three-storey building structure demonstrate the potential to apply the developed technique to the detection and location of damage in practical MDOF engineering structures
Influence of Carbon Concentration on the Superconductivity in MgCxNi3
The influence of carbon concentration on the superconductivity (SC) in
MgCNi has been investigated by measuring the low temperature specific
heat combined with first principles electronic structure calculation. It is
found that the specific heat coefficient of the
superconducting sample () in normal state is twice that of the
non-superconducting one (). The comparison of measured
and the calculated electronic density of states (DOS) shows that the
effective mass renormalization changes remarkably as the carbon concentration
changes. The large mass renormalization for the superconducting sample and the
low (7K) indicate that more than one kind of boson mediated
electron-electron interactions exist in MgCNi.Comment: 4 pages, 4 figure
Band Structure Asymmetry of Bilayer Graphene Revealed by Infrared Spectroscopy
We report on infrared spectroscopy of bilayer graphene integrated in gated structures. We observe a significant asymmetry in the optical conductivity upon electrostatic doping of electrons and holes. We show that this finding arises from a marked asymmetry between the valence and conduction bands, which is mainly due to the inequivalence of the two sublattices within the graphene layer and the next-nearest-neighbor interlayer coupling. From the conductivity data, the energy difference of the two sublattices and the interlayer coupling energy are directly determined
Study of J/psi decays to Lambda Lambdabar and Sigma0 Sigma0bar
The branching ratios and Angular distributions for J/psi decays to Lambda
Lambdabar and Sigma0 Sigma0bar are measured using BESII 58 million J/psi.Comment: 11 pages, 5 figure
The Effects of Linear and Nonlinear Characteristic Parameters on the Output Frequency Responses of Nonlinear Systems: The Associated Output Frequency Response Function
In the present study, a new concept known as the Associated Output Frequency Response Function (AOFRF) is introduced
to facilitate the analysis of the effects of both linear and nonlinear characteristic parameters on the output frequency
responses of nonlinear systems. Based on the AOFRF concept, the study has shown, for the first time, that the output frequency
responses of a wide class of nonlinear systems that are described by the NARX (Nonlinear Auto Regressive with
eXegenous input) model can be represented by a polynomial function of both the system linear and nonlinear characteristic
parameters of interests to the system analysis. Moreover, an efficient algorithm is derived to determine the structure and coefficients
of the AOFRF based representation for system output frequency responses. Finally, a case study is provided to
demonstrate the effectiveness and advantages of the new AOFRF based representation and the implication of the result to
the analysis and design of nonlinear systems in the frequency domain
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