喷射器设计与使用管理中的一种特殊现象研究

基于大量试验发现了喷射器扩压管喉径与喷嘴喉径匹配过程中存在的中间迟钝现象,并对它进行了较深入的研究。结果表明,这一现象的出现时机主要取决于喷嘴喉径、出入口流体的压力及压差;在对大量试验数据按数值方法进行处理后,得出了中间迟钝现象出现时机的简易判据。应用这一研究,可以有效减少喷射器设计的工作量,提高设计效率;可以形象地说明喷射器实际工况偏离设计点时效率下降的原因;还可用于指导喷射器变工况下的使用管理,减小变工况下工作调节的盲目性。     

Viscometer using drag force measurements

A robust and precise viscometer using the forces exerted by a laminar flow inside a small duct is presented: the force is measured on a long cylindrical sensor dipped into the flow. Two devices of respective volumes 1.4 and 0.031?ml have been realized, demonstrating that the technique is usable with small fluid volumes. Several Newtonian and non-Newtonian fluids have been tested at shear rates ranging from 0.3 to 10?s(-1) for the first device and from 85 to 2550?s(-1) for the second one. For Newtonian fluids, of viscosities ranging from 10(-3) to 0.1?Pa?s, the linear response of the device has been verified and a 90% agreement with the values provided by commercial rheometers is obtained. For non-Newtonian polymer solutions, the variation of the force with the flow velocity allows one to determine the dependence of the viscosity on the shear rate. Two shear thinning polymer solutions with a power law behavior at intermediate shear rates have been investigated and their rheological parameters have been determined.     

矿用机械式挖掘机动态测试传感器的研制

本文根据大型矿用机械式挖掘机动态测试方案的要求，开发研制出一种新型的推压力传感器，解决了大型挖掘机国产化研究中动态测量这一关键性技术难题。传感器结构新颖独特，性能良好在矿山机械和工程机械中具有广泛地应用价值。     

金属氧化物对镉电极的影响

本文研究了几种金属氧化物对镉电极活性物质利用率以及对密封Cd/Ni蓄电池荷电保持能力的影响。结果表明,镉电极中添加MgO、ZnO和Fe_2O_3可提高活性物质利用率;添加o_2O_3则显著降低活性物质利用率。MgO、In_2O_3和ZnO的添加,提高了密封Cd/Ni蓄电池的荷电保持能力;Co_2O_3和Fe_2O_3的添加,降低了其荷电保持能力。最后,探讨了MgO和ZnO在镐电极中的适宜添加量。     

Architecture of a Memory Manager for an MPEG-2 Video Decoding Circuit

A study of the MPEG-2 video decoding standard in Main Profile @ Main Level has been performed, comparing the different solutions existing for the VLSI implementation of the basic functions (Huffman decoding, IDCT...) included in the standard. Afterwards, a new dynamically configurable architecture is proposed for the memory manager, which is necessary to deal with the large data flow inside the decoder. It is aimed at interfacing the external memory, arbitrating the access requests coming from the different decoding units and allowing generic memory requests through the definition of virtual addresses. It is shown that, by means of a particular data organization, the circuit requires an external memory, which is a 2-MB DRAM in fast page or EDO mode, accessible via a 64-bit bus. The memory manager works at 27 MHz and allows a real-time decoding for MP @ ML bitstreams. It has been synthesized in a 0.8-m two-metal CMOS technology and presents a total area of 5.4 mm2 for 6500 gates.     

Early diagnosis of Alzheimer's disease

The diagnosis of dementia of Alzheimer type (DTA) in the early stage of the disease may be possible with the development of specialized memory consultations. After this diagnosis, we can inform family and even the patient in some cases, monitor the progression of disease, give or not treatment, and help family for daily life management (money, car driving, administration papers, etc.). The first step is to analyse the memory complaints of the patient and if possible of his family. The difficulties in everyday life are more informative than an anxious complaint of memory and some IADL deficiency appear early: difficulty to use phone, drugs, transports or checks. The patient examination by a practitioner or a neurologist has to be complete, even if normal in most of the cases. The practitioner has to explore without specific material, the main cognitive domain: the "5 words test" illustrates a useful memory tool, analysing two types of recall. We also must observe writing, digit span, naming and verbal fluency. The examination by a psychologist using standardized batteries of tests must always be driven by this clinical exploration using common scales like MMS or ADAS. In very early DTA, we may observe a cognitive decline limited to some aspects of memory (free long term recall, cued recall, working memory...) with a decline of the most controlled attentional tasks. An isolated memory disorder has to be identified either as onset of DTA or as an aging related cognitive decline (ARCD): the difference is qualitative and may appear only on repeated exams by experimented psychologist.     

Simulation and fabrication of attenuated phase-shifting masks: CrF(x)

To acquire the required resolution for 248- and 193-nm lithography, a study of attenuated phase-shifting mask (Att-PSM) technology is in progress. We performed a simulation study using a matrix method to calculate relative transmittance and the amount of phase shift of light through the PSM. However, we found that the average film composition changed with deposition time. Accordingly, optical constants were found to be a strong function of film thickness. Therefore we rearranged the relationship between deposition parameters (e.g., deposition time or gas flow rate ratio) and optical constants (e.g., refractive index and extinction coefficient) to extract the empirical formula for the optical constants with respect to film composition. To verify our simulation study, we fabricated a phase shifter based on our simulation result, which was found to have a transmittance of 8.3% and a phase shift of 179.5 degrees . Consequently, we obtained a reliable optimum condition for the deep-ultraviolet Att-PSM.     

Ka and Q band propagation experiments in Toulouse using ASTRA 3B and ALPHASAT satellites

From January 2008 to March 2011, ONERA operated in Toulouse, France, a beacon receiver able to collect the 19.7‐GHz beacon signal of the HotBird 6 satellite. In March 2011, the radio frequency chain was modified to be able to receive the 20.2‐GHz ASTRA 3B beacon to benefit from a higher Equivalent Isotropically Radiated Power of the satellite. Since June 2015, a second beacon receiver has been installed and is able to record the 39.4‐GHz beacon signal of the Alphasat satellite. The objective of this paper is to present the results of the first 2 years of measurements (June 2015 to May 2017) of the Q‐band Alphasat propagation experiment in Toulouse, as well as concurrent measurements collected at Ka‐band with ASTRA 3B. First of all, the propagation experiments are briefly described. Second, the results of the statistical analysis are highlighted. Finally, a deep analysis of the performances of the 2 frequency scaling prediction methods recommended in ITU‐R P.618‐13 is performed.     

Symmetry Modulation and Enhanced Multiferroic Characteristics in Bi1‐xNdxFeO3 Ceramics

BiFeO₃ is recognized as the most important room temperature single phase multiferroic material. However, the weak magnetoelectric (ME) coupling remains as a key issue, which obstructs its applications. Since the magnetoelectric coupling in BiFeO₃ is essentially hindered by the cycloidal spin structure, here efforts to improve the magnetoelectric coupling by destroying the cycloidal state and switching to the weak ferromagnetic state through symmetry modulation are reported. The structure is tuned from polar R3c to polar Pna2₁, and finally to nonpolar Pbnm by forming Bi_1‐xNd_xFeO₃ solid solutions, where two morphotropic phase boundaries (MPBs) are detected. Greatly enhanced ferroelectric polarization is obtained together with the desired weak ferromagnetic characteristics in Bi_1‐xNd_xFeO₃ ceramics at the compositions near MPBs. The change of magnetic state from antiferromagnetic (cycloidal state) to ferromagnetic (canted antiferromagnetic) is confirmed by the observation of magnetic domains using magnetic force microscopy. More interestingly, combining experiments and first‐principles‐based simulations, an electric field‐induced structural and magnetic transition from Pna2₁ back to R3c is demonstrated, providing a great opportunity for electric field‐controlled magnetism, and this transition is shown to be reversible with additional thermal treatment.