Abstract: A method for determining a far-field signature FF(t) of a plurality of N seismic sources Si (i=1, . . . , N) comprises a stage of measuring a near-field signature NFi(t) of each seismic source Si. In a preliminary stage an initial near-field signature NFio(t) of each seismic source Si and an initial far-field signature FFo(t) of the plurality of N seismic sources are measured simultaneously. An operator G is determined, defined by the convolution integral ##EQU1## The near-field signature NFi(t) measuring stage is carried out on each firing of the N seismic sources Si.

Abstract: In a multisource array of seismic sources, each source is associated with one or more sensors (Ci) for picking up the impulses (TB or signature) emitted by the associated source when triggered. The apparatus essentially includes one or more acquisition arrays (Ai), each one associated with a storage unit (Mi) for all the signals emitted by the pickups (Ci) under the control of a computer (10). Each memory unit includes a comparison module (19, 21, 22) for comparing the digitized samples with a threshold value. The number of each one of the channels where a threshold overrun has occurred is recorded in a reference register (24) which is systematically read by the computer. This monitoring of the level of the picked up signals is carried out outside the normal period where the sources are triggered.

Abstract: Each source of an array of seismic signal sources is associated with one or several sensors (Ci) which pick up the impulses the associated source emits at the time of triggering. The device essentially includes an apparatus (6) for the acquisition and the storage of all the signals emitted by the sensors (Ci) and a shooting control apparatus (7), having memories for reference data, for triggering the seismic sources according to these reference data. A computer (10) is programmed to determine the reference data used for the triggering, preferable according to the signals from the sensors (Ci) acquired during the previous emission cycles and validated in order to check whether their form and/or arrival times are within fixed limits. This arrangement makes it possible to take into account the real working conditions of the emission array. The invention can be utilized in marine seismic prospecting.

Abstract: A facsimile transmitter capable of transmitting graphic as well as text material, by telephone or wireless. A digital code derived from scanning the document to be transmitted is truncated from eight bits per pixel to six bits per pixel. The three most significant bits of each pixel are run length encoded in eight bit bytes, so that wherever the same three most significant bits appear in adjacent pixels, these three bits are transmitted once, followed by a five bit code indicating the number of times (up to 32 times) the same three most significant bits are repeated in succeeding pixels. The resulting eight bit bytes are similarly run length encoded, so that the transmission of the three most significant bits of each pixel is double run length encoded. An eight bit fine resolution byte is transmitted for each eight pixels.

Abstract: The present invention concerns a process for the recreation of an analog luminance signal from a digital signal used for transmission after analog digital conversion of a luminance signal representative of a document to be transmitted, consisting in taking into consideration, before or after the D-A conversion of the reception, a number P of successive pixels P-2, P-1, P, P+1, p+2 and, as a function of their relative and absolute amplitudes, in processing the central pixel P, breaking it down into m sub-pixels having densities that are a function of those of the surrounding pixels. The present invention notably applies to the digital transmission of iconographic documents transmitted and received by a method of the "Belin" type.

Abstract: Method for the reconstitution, by filtering, of an analog signal, from a udo-analog signal obtained by a double, analog to digital, digital to analog conversions of the analog signal, with processing of the digital signal. In greater detail, the pseudo-analog signal, obtained by double analog to digital, digital to analog conversion of an analog signal, is applied to an active filter the impedance of which is controlled by the absolute derivative of the positive value of the pseudo-analog signal. The derivative is obtained by a circuit comprising an RC filter receiving the pseudo-analog signal and a memory controlling the value of the impedance of the filter. The invention has particular application to the restitution of graphic or iconographic documents which have been previously digitally encoded.

Abstract: Depolymerized cellulose powder having substantially an amorphous structure which is obtained by letting cellulose fibers dissolve in concentrated hydrochloric acid of about 40% and at a temperature of at least 38.degree. C. A homogeneous acid hydrolysis is carried out under well controlled conditions in order to depolymerize the dissolved cellulose and is stopped when the cellulose has achieved a mean degree of polymerization between 10 and 200. The depolymerized dissolved cellulose is then separated and processed in order to obtain the aforesaid powder of amorphous depolymerized cellulose.

Abstract: Continuous hydrolysis to produce sugars is effected by cyclically immersing a solid, divided lignocellulosic material in a bath of concentrated hydrochloric acid and draining the material between successive immersions so as to dissolve the produced sugars, until the sugar concentration of the acid in the bath has attained a desired value.The solid material and the liquid acid are delivered to a tubular horizontal rotary reactor arranged to provide a bath of the acid, to produce a rotating movement for cyclical immersion of the solid material in the bath of acid and longitudinally displace the solid material undergoing hydrolysis together with the acid of the bath and to continuously discharge solid residue and acid containing dissolved sugars due to overflow by gravity at an outlet end of the reactor.

Abstract: A fragmented material is dissolved continuously by impregnation and immersion into a solvent bath in which said material is subjected to a moderate mixing movement allowing it to be kept within the interior of said bath to undergo dissolution therein until formation of fine residual particles of insoluble material which are maintained in suspension by this movement, the whole being removed continuously by a controlled overflow of the bath. This process is applied to cellulose contained in various lignocellulosic materials, which is dissolved continuously by immersion of the previously impregnated material into a bath of hydrochloric acid through which hydrogen chloride gas is caused to bubble, to effect complete dissolution of the cellulose and suspension of the fine insoluble residual lignin particles.

Abstract: A process for the preparation of lactosylurea and the N-methylol derivative thereof which are usable as feed supplements for ruminants.According to this process, lactose and urea are heated to 70.degree.-110.degree. C. with a minimum of water and, if possible, this water is eliminated during the reaction. The crude reaction product can be purified by grinding with ice-water or ethanol and subsequent draining so as to eliminate by dissolution in such solvants the unreacted urea.The corresponding N-methylol derivative is obtained by the reaction with formaldehyde.

Abstract: Continuous hydrolysis to produce sugars is effected by cyclically immersing a solid, divided lignocellulosic material in a bath of concentrated hydrochloric acid and draining the material between successive immersions so as to dissolve the produced sugars, until the sugar concentration of the acid in the bath has attained a desired value.The solid material and the liquid acid are delivered to a tubular horizontal rotary reactor arranged to provide a bath of the acid, to produce a rotating movement for cyclical immersion of the solid material in the bath of acid and longitudinally displace the solid material undergoing hydrolysis together with the acid of the bath and to continuously discharge solid residue and acid containing dissolved sugars due to overflow by gravity at an outlet end of the reactor.

Abstract: Feedstuff for livestock containing essentially carbohydrates (starches and cellulose based products) and glucosylurea of more than 90% purity. The glucosylurea is obtained by the condensation under acidic conditions of urea and glucose and the addition of 30-50% water which results, after final concentration and cooling, in the crystallization of pale yellow glucosylurea.

Abstract: Continuous hydrolysis to produce sugars is effected by cyclically immersing a solid, divided lignocellulosic material in a bath of concentrated hydrochloric acid and draining the material between successive immersions so as to dissolve the produced sugars, until the sugar concentration of the acid in the bath has attained a desired value.The solid material and the liquid acid are delivered to a tubular horizontal rotary reactor arranged to provide a bath of the acid, to produce a rotating movement for cyclical immersion of the solid material in the bath of acid and longitudinally displace the solid material undergoing hydrolysis together with the acid of the bath and to continuously discharge solid residue and acid containing dissolved sugars due to overflow by gravity at an outlet end of the reactor.