THM and HAA formation from NOM in raw and treated surface waters

The disinfection by-product (DBP) formation potential (FP) of natural organic matter (NOM) in surface water sources has been studied with reference to the key water quality determinants (WQDs) of UV absorption (UV254), colour, and dissolved organic carbon (DOC) concentration. The data set used encompassed raw and treated water sampled over a 30-month period from 30 water treatment works (WTWs) across Scotland, all employing conventional clarification. Both trihalomethane (THM) and haloacetic acid (HAA) FPs were considered. In addition to the standard bulk WQDs, the DOC content was fractionated and analysed for the hydrophobic (HPO) and hydrophilic (HPI) fractions. Results were quantified in terms of the yield (dDBPFP/dWQD) and the linear regression coefficient R2 of the yield trend. The NOM in the raw waters was found to comprise 30–84% (average 66%) of the more reactive HPO material, with this proportion falling to 18–63% (average 50%) in the treated water. Results suggested UV254 to be as good an indicator of DBPFP as DOC or HPO for the raw waters, with R2 values ranging from 0.79 to 0.82 for THMs and from 0.71 to 0.73 for HAAs for these three determinants. For treated waters the corresponding values were significantly lower at 0.52–0.67 and 0.46–0.47 respectively, reflecting the lower HPO concentration and thus UV254 absorption and commensurately reduced precision due to the limit of detection of the analytical instrument. It is concluded that fractionation offers little benefit in attempting to discern or predict chlorinated carbonaceous DBP yield for the waters across the geographical region studied. UV254 offered an adequate estimate of DBPFP based on a mean yield of ∼2600 and ∼2800 μg per cm−1 absorbance for THMFP for the raw and treated waters respectively and ∼3800 and2900 μg cm−1 for HAAFP, albeit with reduced precision for the treated waters

Pilot-scale spiral wound membrane assessment for THM precursor rejection from upland waters

The outcomes of a pilot-scale study of the rejection of trihalomethanes (THMs) precursors by commercial ultrafiltration/nanofiltration (UF/NF) spiral-wound membrane elements are presented based on a single surface water source in Scotland. The study revealed the expected trend of increased flux and permeability with increasing pore size for the UF membranes; the NF membranes provided similar fluxes despite the lower nominal pore size. The dissolved organic carbon (DOC) passage decreased with decreasing molecular weight cut-off, with a less than one-third the passage recorded for the NF membranes than for the UF ones. The yield (weight % total THMs per DOC) varied between 2.5% and 8% across all membranes tested, in reasonable agreement with the literature, with the aromatic polyamide membrane providing both the lowest yield and lowest DOC passage. The proportion of the hydrophobic (HPO) fraction removed was found to increase with decreasing membrane selectivity (increasing pore size), and THM generation correlated closely (R2 = 0.98) with the permeate HPO fractional concentration

PID, 2-DOF PID and mixed sensitivity loop-shaping based robust voltage control of quadratic buck DC-DC converter

DC-DC Quadratic Buck Converter (QBC) is largely used in applications where the high step-down conversion ratio is required. In the practical implementation, QBC is subject to uncertainties, disturbance, and sensor noise. To address the QBC control problems, a two-degree of freedom PID (2-DOF PID) is designed in the robust control framework. Further, for comparison purpose, a one-degree of freedom PID (1-DOF PID) and mixed sensitivity loop-shaping (MS-LS) controller are also proposed. Considering QBC parasitic components, the QBC small-signal transfer function is derived based on a practical approach. Sensitivity functions are used to specify the desired design requirements, and non-smooth optimization is used to tune both PID's parameters. The three control structures are implemented and tested in the Matlab/Simulink environment. As attested by simulation results, the 2-DOF PID exhibits a better regulation accuracy with enhanced robust stability and robust performance for a wide range of supply voltage/load variation and sensor noise effect

Optimizing protections against cascades in network systems: A modified binary differential evolution algorithm

International audienceThis paper addresses the optimization of protection strategies in critical infrastructures within a complex network systems perspective. The focus is on cascading failures triggered by the intentional removal of a single network component. Three different protection strategies are proposed that minimize the consequences of cascading failures on the entire system, on predetermined areas or on both scales of protective intervention in a multi-objective optimization framework. We optimize the three protection strategies by devising a modified binary differential evolution scheme that overcomes the combinatorial complexity of this optimization problem. We exemplify our methodology with reference to the topology of an electricity infrastructure, i.e. the 380 kV Italian power transmission network. We only focus on the structure of this network as a test case for the suggested protection strategies, with no further reference on its physical and electrical properties

Milestones in the History of Intelligence – Oradea as a Nodal Centre on the Regional Geopolitical Axis in the Security Equation

The East European region has always created a space of interaction between the great powers of the Eastern and Western Europe of the different epochs in European history. Not just a contact and an interaction region between Europe, Asia and the Middle East (Africa), but also a pivot of the European security environment, most often forming a real axis on which this scene of confrontation between powers can bend into one or the other part. We can say that the Eastern European region has formed hundreds of years ago (with the emergence of Ottoman power and its pressure on the Western powers, the emergence of the Tsarist and later Soviet power) a pivotal axis which determined the geopolitical configuration of the world and led successively to the advancement or decay of an empire or another. Indeed, the balance between Western powers and the Ottoman Empire, and later between the Austro-Hungarian Empire and the Eastern Powers, such as the Ottoman Empire and the Tsarist Empire, has been established for several hundred years right in this pivotal axis of Eastern Europe. For this reason, the political and military situation of the territories covered by the pivotal axis have always been a special one. This pivotal axis of Europe started from the Baltic Sea and was generally disposed over the continental strip where today are countries like Estonia, Latvia and Lithuania, a part of Poland (Pomerania and a part of Silesia), the Czech Republic, the western part of today Romania and a part of Serbia. This geographical positioning of the pivotal axis has led to a permanent political turmoil and change of borders in the mentioned regions. Referring exclusively to the manner in which this pivot axis intersected the current territory of Romania, we observe that in its passage from north to south it included Satu Mare, Oradea, Arad, Timişoara and Reşita. Oradea has always played an important role in Central-Eastern Europe, NATO recognizing the NATO HUMINT Centre of Excellence (HCOE) as a strategical organization with a remarkable contribution to the development of the Human Intelligence capability within the Alliance

Sliding mode approach for control and observation of a three phase AC-DC pulse-width modulation rectifier

Introduction. For AC-DC conversion systems, the electrical systems typically use thyristor or diode bridge rectifiers, which have relatively poor performance. Nowadays, three-phase pulse-width modulation rectifiers are widely applied in various applications for their well-known intrinsic benefits, such as adjustable DC link voltage, unity power factor, bidirectional power flow and very low total harmonic distortion. Purpose. The objective of this work is to achieve better stability and dynamic performance using sliding mode strategy for control and observation. Methods. For that purpose, first a sliding mode controller is introduced on the DC-link side to ensure a fast and accurate response of the output load voltage. Then, the sliding mode approach is employed to control the quadrature and direct components of power to maintain the input power factor at unity. Finally, this approach is used to design two observers for grid voltage estimation and online variation of load resistance. To overcome the problem associated with the use of the classical low-pass filter, an adaptive compensation algorithm is used to compensate the attenuation of the amplitude and phase delay of the observed grid voltages. This algorithm is based on the use of the two low-pass filters in cascade and ensures the minimization of chattering. Results. Comparative studies have been carried out between sliding mode control method for controlling the three-phase AC-DC pulse-width modulation rectifier and other conventional techniques. The validation by simulation and the tests carried out gave very satisfactory results and proved the effectiveness and feasibility of the sliding mode for both control and observation of three phase pulse-width modulation rectifier.Вступ. Для AC-DC систем перетворення електричні системи зазвичай використовують тиристорні або діодні мостові випрямлячі, які мають відносно погані характеристики. В даний час трифазні випрямлячі з широтно-імпульсною модуляцією широко застосовуються з різними цілями завдяки їх добре відомим внутрішнім перевагам, таким як регульована напруга у ланці постійного струму, одиничний коефіцієнт потужності, двонаправлений потік потужності та дуже низькі загальні гармонічні спотворення. Метою даної роботи є досягнення кращої стабільності та динамічних характеристик з використанням стратегії ковзного режиму для контролю та спостереження. Методи. З цією метою спочатку на стороні ланки постійного струму вводиться регулятор режиму ковзання, щоб забезпечити швидку і точну реакцію на вихідну напругу навантаження. Потім використовується метод ковзного режиму для управління квадратурною та прямою складовими потужності, щоб підтримувати вхідний коефіцієнт потужності рівним одиниці. Нарешті цей підхід використовується для розробки двох спостерігачів для оцінки напруги мережі та зміни опору навантаження в режимі онлайн. Для подолання проблеми, пов'язаної з використанням класичного низькочастотного фільтру, використовується алгоритм адаптивної компенсації, що компенсує загасання амплітуди і фазової затримки напруг мережі, що спостерігаються. Цей алгоритм заснований на використанні двох низькочастотних фільтрів у каскаді та забезпечує мінімізацію брязкоту. Результати. Були проведені порівняльні дослідження між методом керування ковзним режимом для керування трифазним випрямлячем AC-DC з широтно-імпульсною модуляцією та іншими традиційними методами. Перевірка за допомогою моделювання та проведені випробування дали дуже задовільні результати та довели ефективність та здійсненність ковзного режиму як для управління, так і для спостереження за трифазним випрямлячем з широтно-імпульсною модуляцією

Milestones in the History of Intelligence – Oradea as a Nodal Centre on the Regional Geopolitical Axis in the Security Equation

The East European region has always created a space of interaction between the great powers of the Eastern and Western Europe of the different epochs in European history. Not just a contact and an interaction region between Europe, Asia and the Middle East (Africa), but also a pivot of the European security environment, most often forming a real axis on which this scene of confrontation between powers can bend into one or the other part. We can say that the Eastern European region has formed hundreds of years ago (with the emergence of Ottoman power and its pressure on the Western powers, the emergence of the Tsarist and later Soviet power) a pivotal axis which determined the geopolitical configuration of the world and led successively to the advancement or decay of an empire or another. Indeed, the balance between Western powers and the Ottoman Empire, and later between the Austro-Hungarian Empire and the Eastern Powers, such as the Ottoman Empire and the Tsarist Empire, has been established for several hundred years right in this pivotal axis of Eastern Europe. For this reason, the political and military situation of the territories covered by the pivotal axis have always been a special one. This pivotal axis of Europe started from the Baltic Sea and was generally disposed over the continental strip where today are countries like Estonia, Latvia and Lithuania, a part of Poland (Pomerania and a part of Silesia), the Czech Republic, the western part of today Romania and a part of Serbia. This geographical positioning of the pivotal axis has led to a permanent political turmoil and change of borders in the mentioned regions. Referring exclusively to the manner in which this pivot axis intersected the current territory of Romania, we observe that in its passage from north to south it included Satu Mare, Oradea, Arad, Timişoara and Reşita. Oradea has always played an important role in Central-Eastern Europe, NATO recognizing the NATO HUMINT Centre of Excellence (HCOE) as a strategical organization with a remarkable contribution to the development of the Human Intelligence capability within the Alliance