试论中型氮肥厂的技术改造

(一)解放初期,我国仅在大连、南京有两家合成氨厂,合成氨能力约46,000吨,年产氨仅5000吨。三十多年来,中型氮肥厂合成氨生产发展速度很快,各个时期合成氨产量的年平均递增速度是:第一个五年计划为32.5％;第二个五年计划24％;三年调整时期23.5％;第三、四个五年计划7％;第五个五年计划9.2％。1983年底,中型氮肥厂合成氨生产能力为437.5万吨,产量382万吨,负荷率87％。特别应该说明的是:1966至1975年建成投产的新厂29个,加上这期间老厂扩建,共     

Research and Practice of Hybrid Teaching for Software Testing based on Interactive Learning

To address the problems of insufficient number of personalized exercises and cases and teachers' lack of grasp of students' weak knowledge points in the current software testing online courses, we study the strategy of establishing and updating intelligent exercise sets and case libraries and analyze the answers and dig out the weak points of knowledge through group intelligence reasoning and interactive machine learning methods. This will help teachers to make uniform and targeted explanations, reduce manual judgment, and achieve intelligent teaching quality reform, and implement the educational concepts of "keeping up with the times" and "teaching according to students' abilities".     

Slicing-response model for ablation mass removal of polyformaldehyde irradiated by pulsed CO2 laser in vacuum

The interaction between CO2 laser and polyformaldehyde(POM)is quite important in the research of laser irradiation effects and mechanisms.At this time,the accuracy of the existing mass-ablation models for POM irradiated by CO2 laser is poor compared with the experimental data.Based on the energy distribution deposited in the POM target,the active area excited by laser is divided into four slices,the ablation slice(the temperature-rising slice,the perturbation slice,and the undisturbed slice),and a slicing response model for the mass ablation of POM induced by pulsed CO2 laser irradiation in vacuum is developed.A formula is deduced to predict the ablated mass areal density from the model and is verified with data from several studies and our own experiments.The results show that our model fits the experimental data quite well before the shielding effect of ablation products becomes notable.The applicability of the model to other materials and the mass ablation in atmosphere are also briefly explored.     

Resolution improvement in microscopic imaging through turbid media based on differential polarization gating

We report a new method for microscopic imaging of an object embedded in a turbid medium, based on the differential polarization-gating mechanism. It is demonstrated that with this method, image resolution through optically thick milk suspensions can be improved by as much as 30% compared with no-gating methods. An image resolution of tens of micrometers is achieved in an optically thick turbid medium, which is approximately 10 times better than that achieved in transillumination imaging in a similar medium.     

Biotechnological Strategies of Riboflavin Biosynthesis in MicrobesOA

Riboflavin is an essential micronutrient for humans and must be obtained exogenously from foods or supplements. Numerous studies have suggested a major role of riboflavin in the prevention and treatment of various diseases. There are mainly three strategies for riboflavin synthesis, including total chemical synthesis, chemical semi-synthesis, and microbial fermentation, the latter being currently the most promising strategy. In recent years, flavinogenic microbes have attracted increasing attent...     

Phase-shifting apodizers for increasing focal depth

We propose the use of a phase-shifting apodizers to increase focal depth, and we study the axial and radial behavior of this kind of apodizer under the condition that the axial intensity distribution is optimized for high focal depth.     

High focal depth with a pure-phase apodizer

High-density optical data storage requires high-numerical-aperture (NA) lenses and short wavelengths. But, with increasing NA and decreasing wavelength, the depth of focus (DOF) decreases rapidly. We propose to use pure-phase superresolution apodizers to optimize the axial intensity distribution and extend the DOF of an optical pickup. With this kind of apodizer, the expected DOF can be 2-4.88 times greater than that of the original system, and the spot size will be smaller than that of the original system.     

3D printed fiber-optic nanomechanical bioprobe

Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these instruments are limited because of their size and complex feedback system.In this study,we demonstrate a miniature fiber optical nanomechanical probe(FONP) that can be used to detect the mechanical properties of single cells and in vivo tissue measurements.A FONP that can operate i...     

Electrical and thermal transport properties of kagome metals AV3Sb5(A=K,Rb,Cs)

The interplay between lattice geometry,band topology and electronic correlations in the newly discovered kagome compounds AV₃Sb₅(A=K,Rb,Cs) makes this family a novel playground to investigate emergent quantum phenomena,such as unconventional superconductivity,chiral charge density wave and electronic nematicity.These exotic quantum phases naturally leave nontrivial fingerprints in transport properties of AV₃Sb₅,both in electrical and thermal channels,w...