Analyse de la relation de puissance : débit solide - débit liquide à l'échelle du bassin versant de l'Oued Wahrane (Algérie)

Les flux de sédiments en suspension recueillis à l'exutoire d'un bassin versant sont étroitement liés aux débits liquides. Les modèles de relation liant ces deux paramètres reposent sur des concepts similaires faisant intervenir la loi de puissance Y=aXb. Bien que la validité d'une telle relation n'est pas à prouver, une analyse qualitative de la constante a et de l'exposant b a été effectuée pour un bassin versant situé en zone semi - aride : l'Oued Wahrane (Algérie). Les différentes échelles temporelles d'analyse utilisées ont permis d'expliquer le comportement des paramètres de l'équation en vue d'une meilleure compréhension de cette relation et de relier ces paramètres aux facteurs qui induisent le débit solide. L'objectif principal à trait aux aspects théoriques et pratiques du phénomène du transport solide en suspension. Les résultats ont permis d'identifier de manière assez concluante les modèles saisonniers. L'échelle saisonnière est très représentative du phénomène de transport solide dans le bassin versant. D'autres part, l'événement averse-crue s'est avéré l'unité hydrologique la plus adéquate pour les analyses en relation avec le transport solide.Fluxes of suspended materials collected at gauge stations are closely related to flow discharges. In the absence of continuous recorded suspended sediment concentration data, hydrologists have used rating sediment transport curves to define the water discharge/suspended sediment relationship and to estimate (predict) suspended sediment concentrations for use in flux calculations. Although there are many methods for developing rating curves, the most common is a power function Y=aXb that relates suspended sediment concentration to water discharge. The discharge measurement is composed of independent variables and a and b are the intercept and slope of the rating curve, respectively. These rating curves are usually generated by least squares regression. Although the accuracy of this approach has been questioned, the applicability appears to be adequate for many purposes. In order to better understand the relationship, this paper reports a qualitative analysis of parameters a and b.The average suspended sediment load for a cross-section of average stream discharge is the product of the average concentration of the suspended materials and the average flow discharge during the same period. The relation between sediment discharge and water discharge in Algeria rivers is unknown and difficult to assess. Some of these difficulties are related to sampling methods and a continuous record of suspended sediment concentrations is not available. This work will also be used to describe sedimentary dynamics specific to the basin during flood periods. The study was carried out on daily flow discharge data and the concentration of suspended materials collected from the gauging station on the Wahrane River (1972 to 1989). To determine the variation of the parameters a and b of the power relation, a methodology using regression models was used, based on an analysis on various scales of the parameters a and b of the equation of sediment transport in relation to the hydrological characteristics. The analysis reveals the evolution of the parameters a and b. Several temporal scales were used. An examination on an annual scale shows that it was possible to define a very strong relationship between a and the hydraulicity for the dry years and that indeed the factor a, indicating erodability, was well correlated with the hydraulicity during the dry period. The exponent b was correlated with hydraulicity only during the wet period. The relationship between a and mean rainfall was not significant. The seasonal scale revealed a very distinct effect.The production of sediments was very strong in autumn and winter when sediment transport approached the very typical power model. The seasonal rainfall strongly explained the variations of a while the exponent b was related to peak discharge. The analysis carried out on a monthly scale essentially produced the same conclusions as the analysis on a seasonal scale. It was found that the variation of a was more significant in winter and autumn than in the other seasons, presumably because of the hydrologic and sedimentology activity during this period, and the nature and surface quality of the soil. The relation between parameter a and the monthly average rainfall was very good. Given that the storm is the temporal unit most adequate for hydrological analyses in relation to sediment transport, analysis of single hydrologic events in the Wahrane River yields more details on the variation of a and b. The study was extended to the decomposition of the rising and falling limbs of the hydrograms. The floods of March and October showed the evolution of the parameters a and b. First, the range of variation of a and b, which was narrow during the preceding analyses, was broader for the analysis of the rising limb of the hydrograms. Secondly, the values of a and b showed opposite temporal trends. The high values of b were particularly characteristic of the risings associated with the autumn, during which flow discharges are strongest. The risings of winter floods were marked by low values of a. February and December were characterized by lower values of a in the falling limb than in the rising limb and stronger values of b in falling limb. Lastly, analysis of the values of a with respect to the antecedent precipitations index, IPA, suggested that the highest values of a were related to a weak IPA and a strong soil erodability in the catchment, whereas low values of a would reflect soil saturation (i.e. a strong IPA).The study showed that the power relationship between sediment load and stream flow was influenced by precipitation, runoff amount and soil moisture, and illustrated the complexity of solid transport

DISTRIBUTIONS STATISTIQUES DES PLUIES MAXIMALES ANNUELLES DANS LA REGION DU CHELIFF COMPARAISON DES TECHNIQUES ET DES RESULTATS STATISTICAL DISTRIBUTIONS OF ANNUAL MAXIMUM RAINFALLS DEPTHS IN THE AREA OF CHELIFF. COMPARISON OF TECHNIQUES AND RESUL

A statistical analysis of annual series of maximum rainfall depth was carried out on the data of four rainfall stations located in the Central Northern part of Cheliff-Zahrez basin. Two statistical distributions used in sewer system design and floods protection, in the urban and semi urban zones, were retained in this analysis: the generalized extreme values (GEV) distribution and the Gumbel distribution. These laws were adjusted by using local data and by estimating the parameters in a specific method. The methodology used here has been advanced by Koutsoyiannis (2003; 2004). An inter-station and inter technique comparison is being carried out. The results from the two laws are not significantly different. Une analyse statistique des séries annuelles de pluies maximales annuelles a été réalisée sur les données de quatre stations pluviographiques situées dans la partie centrale du Nord du bassin Cheliff-Zahrez. Deux lois de distribution employées dans la conception des réseaux d'assainissement et des aménagements pour la protection contre les inondations, principalement dans les zones urbaines et semi urbaines, ont ainsi été retenues dans cette analyse : la loi des valeurs extrêmes généralisées (GEV) et la loi de Gumbel. Elles ont été ajustées en utilisant des données locales et en estimant les paramètres de manière spécifique. Les résultats issus des deux méthodes ne sont pas significativement différents. Une comparaison inter station est présentée

المشهد الحضري للمدينة بين جدلية التشريع وواقع التطبيق في ظل قانون 08/15 حالة التجزئة الترابية1093مسكن بالمسيلة

سعت الجزائر مع بداية تسعينيات القرن الماضي إلى يومنا هذا، لتنظيم وتحسين الشكل العام لمدنها، من خلال مجموعة من القوانين، والتشريعات. من بين هذه القوانين نجد قانون التهيئة والتعمير رقم 90/29، وقانون التوجيه العقاري رقم 90/25، وبعدها القانون التوجيهي للمدينة 06/06، وآخر القوانين الصادرة نجد القانون 08/15الذي يهدف إلى تحديد مطابقة البنايات وإتمام انجازها، وبالتالي تحسين المظهر الجمالي للمدينة، لكن بعد مرور تسعة سنوات من صدوره، إلا أن واقع معالجة ملفات التسوية لم يحقق  تقدم ملحوظ. ففي مدينة المسيلة مثلا، والى غاية أوت 2017،  تم استقبال 5880 ملف على مستوى لجنة البلدية، لم يقبل منها إلا 347 ملف بنسبة 5.90 %. مما دفعنا إلى التساؤل عن الأسباب الكامنة وراء التأخر في تحقيق الأهداف التي سطرها هذا القانون. للإجابة على التساؤلات المطروح إتصلنا بمختلف الفاعلين خاصة اللجان المعنية بدراسة الملفات والمواطنين، وهذا من خلال دراسة حالة حي 1093 مسكن فردي بالمسيلة.L'Algérie a cherché depuis les années 90 du siècle dernier, jusqu'à nos jours à organiser et à améliorer  la forme générale de ses villes, en adoptant un arsenal de lois et législations .Parmi les importantes lois, on trouve la loi de l'aménagement et de l'urbanisme no 29/90, la loi de l'orientation foncière  no 25/90, puis la loi  d’orientation de la ville no 06/06. La dernière  loi adoptée, la08/15est celle qui fixer les règles de mise en conformité des constructions et leur achèvement, pour  améliorer le paysage urbain de la ville.Mais neuf ans après sa promulgation, la réalité du traitement des dossiers de régularisation n'a pas connu de progrès significatifs. Par exemple au niveau de la ville de M'sila, et jusqu’a la fin de 2017, la commission municipale n'a reçu que 5880 dossiers, seulement 347 dossiers ont été acceptés, ce qui représente 05.90 %uniquement.Cet état de fait nous a poussés à nous interroger sur les raisons de ce retard de régularisation et de réalisation des objectifs fixés par cette loi. Pour répondre aux questions posées, nous avons contacté les différents acteurs, à savoir les commissions chargée des études des dossiers de régularisation, et les citoyens, et ce à travers l’étude de cas de la cité 1093 lots à M'sila

Dosimetric Impact of Intrafraction Motion During Peripheral Lung Cancer Stereotactic Radiotherapy: Is a Second Cone Beam Computed Tomography of Added Value?

PURPOSE/OBJECTIVE(S): In our department, during lung SBRT, all patients (regardless of tumor location) receive an additional intra-fractional CBCT, allowing us to adjust the beam delivery accordingly to the intra-fractional variation (IFV). It is to be expected that each IFV exceeding the planning target volume (PTV) margins could lead to potential discrepancies between planned and delivered plans. A posteriori robust dosimetric evaluation will help us to quantify the actual impact on the target's volumes coverage. MATERIALS/METHODS: Six hundred sixty-four CBCTs from 166 consecutives free-breathing lung SBRT patients were retrospectively analyzed. Treatments were based on the internal target volume (ITV) approach with a 4D-CT at simulation and performed using volumetric modulated arc therapy. An isotropic 0.5 cm margin was used to create the PTV around the ITV. The prescribed dose was 48 Gy in 4 fractions to the PTV (80% isodose line). Patients were divided into two groups: patients for whom the 3D-IFV was below 0.5 cm (low-risk group: 105 patients, 573/664 fractions) and patients with at least one 3D-IFV ≥ 0.5 cm (high-risk group: 61 patients, 91/664 fractions). Plans simulating the dosimetric impact of the IFV were created as follows: the original two arcs were copied into a new plan consisting of 4 times ARC1 and 4 times ARC2. The delivery of ARC1 was always assumed to have occurred with the isocenter coordinates as those in the original plan, whereas the positions of ARC2 were modified for each arc by the measured the 3D displacement for that fraction according to the intra-fraction CBCT. RESULTS: The IFV reduces both the minimal (D99%) and mean (Dmean) dose to both the PTV and the ITV. For the PTV, we obtained: D99(%) = 45.2 vs 48.2 Gy (P 0.5 cm was observed for 3 and 4 fractions, respectively. Regarding the organs at risk (D99%; Dmean; Dmax): for both the low- and high-risk groups, dose-volume histograms were near-identical (no significant difference). CONCLUSION: Although IFV results in a significant change between the delivered vs planned dose distributions for the PTV (D99%; V48Gy; Dmean) and on the ITV (D99%; Dmean), the V48Gy-ITV coverage did not statistically change. Based on our data we demonstrated that a single CBCT is sufficient and reliable to manage the IFV during peripheral lung SBRT.SCOPUS: ar.jDecretOANoAutActifinfo:eu-repo/semantics/publishe

Magnetic properties of the multiferroic double perovskite lead iron niobate: Role of disorder

The peculiarities of the magnetism of one of the first known and most studied multiferroic compounds remain a challenge for solid-state theory. The antiferromagnetic ordering of PbFe1/2Nb1/2O3(PFN) occurs at T-N approximate to 150 K. On the one hand, this value is much larger than the T-N value for most of the other double perovskites. On the other hand, it is significantly lower than theoretical estimates. The temperature dependence of magnetic susceptibility is substantially different from that one expected for conventional antiferromagnets. In order to find the solution of these puzzles, several density functional theory calculations of the magnetic interactions in PFN are reported. The interactions between first-, second-, third- and fourth-neighbor Fe3+ ions (S = 5/2) are calculated. The magnetic response of Fe spins is shown to depend both on the interaction value and the mutual spin arrangement. The magnetic susceptibility of various spin lattices is calculated using the tenth-order high-temperature expansion method and compared with the experiment. A substantial role of disorder for the understanding of the magnetic properties is discussed

Guaianolide and pseudoguaianolide from Pulicaria Iaciniata

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