Identification of machine–tool–workpiece system dynamics

The aim of this paper is to present a method to identify the dynamics of a structure composed of a milling machine, a tool and a workpiece. The excitation is obtained as a result of the interrupted cutting of a narrow workpiece width and single tooth milling operations. This provides a pulse-like cutting force. The three components of the cutting force and the relative motion between the tool and the workpiece are measured simultaneously. A method was developed to determine the nine terms of the structural transfer matrix under a single cutting operation and without any assumption on the excitation direction. The proposed method is experimentally validated.     

Design of dedicated seven-port star dividers for sectored circular antenna array feeding

In order to mitigate the multipath propagation problems for high rate wlans such as Hiperlan (5 GHz) [2], we study an approach based on electronic beam steering over 360° in azimuth with the help of circular arrays of monopoles [3]. Design simplicity and size constraints intended for potential low-cost applications on the terminals has led us to favor a beam switching topology, using a single feeding-port [4]. Two competing configurations of the microstrip feeding circuit are presented and their principle of operation is experimentally validated through passive circuit configurations. The power distribution is achieved in the first one with the help of a pseudo-divider based on a modified 7-branch star junction, whose specific advantage is its very small size. Unfortunately, this design does not preserve the circular permutation invariance of the radiation patterns. The second circuit bypasses this problem in achieving a power distribution through a virtual point junction, at the cost of an appreciable increase in the circuit size.     

Good pharmaceutical manufacturing practices

In order to assure the quality of medicines and to encourage the implementation of the international system for the certification of the quality of pharmaceuticals, it was deemed necessary to specify the conditions under which pharmaceutical establishments should operate to provide full assurance that their products are safe for public health.

The French Government Order of 1. October. 1985 therefore provides for the establishement of new recommendations on good pharmaceutical manufacturing practices: “Bonnes Pratiques de Fabrication et de Production Pharmaceutiques: BPF 1985”.

Within the system of quality assurance, good pharmaceutical manufacturing practices represent that part which is concerned with manufacture.

Their implementation requires that the specification of the raw materials and packaging materials, the manufacturing and packaging processes and the control methods be defined and written beforehand, that the premises and equipment be adapted to the intended uses and that the staff have received appropriate training.

Good pharmaceutical manufacturing practices directly concern production departments and packing area, control laboratories, storage areas, purchasing departments, departments receiving raw materials and dispatching finished products. They also concern departments issuing instructions and written or computerised documents intended for the departments previously mentioned.

Although the collection of recommendations thus published constitutes a detailed document, the possibility of there being different methods for attaining the same objective is recognised.     

PWR steam generator R&D in France: thermal-hydraulic and vibratory aspects

Concomitant with the launching of the French pressurized water reactor (PWR) nuclear power program, a large research and development (R&D) effort was initiated, devoted to the steam generators (SGs). This program, managed cooperatively by Framatome, the SG designer and manufacturer; Electricité de France (EDF), the French electrical utility; and the Commissariat à l'Energie Atomique (CEA), the French Atomic Energy Commission, primarily responsible for nuclear research; was focused on four main objectives:

1. (1) To obtain a better understanding of the physical phenomena existing in these steam generators and leading to SG performance alterations or operating life reductions.

2. (2) To test and validate improved design solutions for the model 51 Framatome steam generator, which was the first one designed under Westinghouse license.

3. (3) To test and validate new Framatome SG designs.

4. (4) To test and validate new, high-performance design tools.

This vast R&D program covers the following theses:

• - SG thermal-hydraulics,

• - SG tube vibration and wear,

• - SG materials (production, corrosion, etc.),

• - Primary and secondary fluid chemistry,

• - SG technology (manufacturing processes, NDT, etc.),

• - SG in-service inspection, and

• - SG maintenance.

These themes are too numerous to be dealt with in a single article. Consequently, the present article will focus on only the first two themes.     

Critères généraux de conception des réseaux de diodes lasers à rubans couplés par champs évanescents

The aim of this article is to define the general criteria for design of phase-locked diode laser arrays. A general method for designing these devices is presented using the effective index method and the coupled mode theory. The confinement required for the individual diodes is defined, and the allowed structure geometries are determined.     

Ancient Analogues of Modern Cement: Calcium Hydrosilicates in Mortars and Concretes from Gallo–Roman Thermal Baths of Western France

The long-term durability of cementbased materials over periods of time not directly accessible to laboratory experiments has to be thoroughly assessed to guarantee the safety of a radioactive waste repository. In this work, archaeological mortars and concretes have been studied to check whether their use as analogues of actual technological cements used for waste disposal is possible. Samples of mortar and concrete have been collected from several Gallo-Roman thermae of western France; they were examined as petrographically thin sections with optical microscopy and were analyzed by X-ray diffraction of microsamples (10⁻³ mg) and by electron probe microanalysis. The masonry cement appears to be entirely carbonated with large voids and fissures. In contrast, the use of lime with additional crushed brick or tile for the bath structure concrete and coating mortar induced pozzuolanic reactions. Despite the fact that the matrices are essentially composed of calcium carbonate, calcium aluminosilicates with compositions close to those of hydrogrossular, hydrated calcium silicates with composition and a structure comparable with those of calcium hydrosilicate formed in modern cement, and ettringite deposits in voids of concretes could also be identified. It is suggestea that these ancient artifacts can help identify very slow processes that rule cement alteration over long periods of time. The artifacts may be considered as possible analogues of present-day materials whenever sufficient care is taken in interpreting and extrapolating data.     

Combination of multi-model predictive control and the wave theory for the control of simulated moving bed plants

In this work a new approach to the control of simulated moving bed (SMB) chromatographic separation processes is presented. This approach is based on the combination of the wave theory and Multi-Model Predictive Control (MMPC). The wave theory provides the theoretical framework in which the control law is formulated whereas receding-horizon MPC is used for determining the appropriate controller parameters. As SMB plants are distributed parameter systems (DPS) with nonlinearity arising from the expression of the adsorption isotherms, classical numerical methods for the solution of DPS are computationally demanding for MPC purposes. Reduced-order models are therefore derived using the proper orthogonal decomposition (POD) technique. To ensure stability, the POD model is updated on-line, resulting in MMPC.     

Mechanism of retention of hydrocarbons in reservoir rocks. Role of polar compounds and effect of additives

Evidence is given for the involvement of hydrophobic interactions in the retention of hydrocarbons in oil fields. A prerequisite is that the surface of the reservoir rock has to be hydrophobic. This was obtained through adsorption of lipophilic polar compounds. The isotherms for the adsorption of dodecylamine hydrochloride and N-hexadecylpyridine hydrochloride were plotted. The treated quartz could take up large amounts of toluene. The relationships between some features of the isotherms and the retention phenomenon have been analysed. The effect of water-structuring additives (e.g. LiF, CaCl₂, NaF and guanidine hydrochloride) on the recovery of hydrocarbons was investigated by means of static and dynamic methods.