bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary Optimization of Colebrook’s Turbulent Flow Friction Approximations
Authors: Brkić Dejan , Ćojbašić Žarko
Published: March 2017

Today, Colebrook’s equation is mostly accepted as an informal standard for modeling of turbulent flow in hydraulically smooth and rough pipes including transient zone in between. The empirical Colebrook’s equation relates the unknown flow friction factor (λ) with the known Reynolds number (R) and the known relative roughness of inner pipe surface (ε/D). It is implicit in unknown friction factor (λ). Implicit Colebrook’s equation cannot be rearranged to derive friction factor (λ) directly and therefore it can be solved only iteratively [λ=f(λ, R, ε/D)] or using its explicit approximations [λ≈f(R, ε/D)]. Of course, approximations carry in certain error compared with the iterative solution where the highest level of accuracy can be reached after enough number of iterations. The explicit approximations give a relatively good prediction of the friction factor (λ) and can reproduce accurately Colebrook’s equation and its Moody’s plot. Usually, more complex models of approximations are more accurate and vice versa. In this paper, numerical values of parameters in various existing approximations are changed (optimized) using genetic algorithms to reduce maximal relative error. After this improvement computational burden stays unchanged while accuracy of approximations increases in some of the cases very significantly.
Enhanced Plant Performance in Cicer arietinum L. due to the Addition of Combination of Plant Growth Promoting Bacteria
Authors: Pérez-Fernández María , Alexander Valentine
Published: March 2017

Six bacterial strains with differing abilities to produce varying concentrations of Indole Acetic Acid were tested individually and in consortia for plant growth promoting and fitness related traits of Cicer arietinum. In all experiments the presence of the nitrogen fixer Mesorhizobium ciceri resulted in increased biomass production.  In the absence of this strain, IAA Psedomonas putida and Bacillus megaterium hinder plant growth and fitness related traits. The application of mixes of the three strains always resulted in better plant performance when M. ciceri was present. Whereas P. putida has a noticeable plant growth-promoting effect B. megaterium resulted less effective. The low levels of IAA produced by the selected strains had a significantly greater positive effect on plant biomass accumulation, flower, pods and seed production as well as on total plant nitrogen and nitrogen concentration in seed than high IAA producer strains.
Influence of the Electrolyte Concentration on the Smooth TiO2 Anodic Coatings on Ti-6Al-4V
Authors: Vera María Laura , Colaccio Ángeles , Rosenberger Mario Roberto , Schvezov Carlos Enrique , Ares Alicia Esther
Published: March 2017

To obtain smooth coatings of TiO2 for building a new design of Ti-6Al-4V heart valve, the anodic oxidation technique in pre-spark conditions was evaluated. TiO2 coating is necessary for its recognize biocompatibility and corrosion resistance. A required feature on surfaces in contact with blood is a low level of roughness (Ra ≤ 50 nm) that not favor the formation of blood clots. The present paper compares the coatings obtained by anodic oxidation of the Ti-6Al-4V alloy using H2SO4 at different concentrations (0.1 M to 4 M) as electrolyte and applying different voltages (from 20 V to 70 V). Color and morphological analysis of coatings are performed using optical and scanning microscopy. The crystalline phases were analyzed by glancing X-ray diffraction. By varying the applied voltage different interference colors coatings were obtained. The differences in morphologies of the coatings, due to the change in concentration, are more evident at high voltages limiting the oxidation conditions for the desired application. Anatase phase was detected from 70 V for 1 M H2SO4. An increase in the concentration of H2SO4 decreases the voltage at which the transformation of amorphous to crystalline coatings occurs, i.e. with 4 M H2SO4 the anatase phase appears at 60 V.
Impacts of Land Cover and Seasonal Variation on Maximum Air Temperature Estimation Using MODIS Imagery
Authors: Cai Yulin , Chen Gang , Wang Yali , Yang Li
Published: March 2017

Daily maximum surface air temperature (Tamax) is a crucial factor for understanding complex land surface processes under rapid climate change. Remote detection of Tamax has widely relied on the empirical relationship between air temperature and land surface temperature (LST), a product derived from remote sensing. However, little is known about how such a relationship is affected by the high heterogeneity in landscapes and dynamics in seasonality. This study aims to advance our understanding of the roles of land cover and seasonal variation in the estimation of Tamax using the MODIS (Moderate Resolution Imaging Spectroradiometer) LST product. We developed statistical models to link Tamax and LST in the middle and lower reaches of the Yangtze River in China for five major land-cover types (i.e., forest, shrub, water, impervious surface, cropland, and grassland) and two seasons (i.e., growing season and non-growing season). Results show that the performance of modeling the Tamax-LST relationship was highly dependent on land cover and seasonal variation. Estimating Tamax over grasslands and water bodies achieved superior performance; while uncertainties were high over forested lands that contained extensive heterogeneity in species types, plant structure, and topography. We further found that all the land-cover specific models developed for the plant non-growing season outperformed the corresponding models developed for the growing season. Discrepancies in model performance mainly occurred in the vegetated areas (forest, cropland, and shrub), suggesting an important role of plant phenology in defining the statistical relationship between Tamax and LST. For impervious surfaces, the challenge of capturing the high spatial heterogeneity in urban settings using the low-resolution MODIS data made Tamax estimation a difficult task, which was especially true in the growing season.
Optimasi Penjadwalan Flow Shop Menggunakan Algoritma Hybrid Differential Evolution
Authors: Nurdiansyah Rudi
Published: March 2017

Penjadwalan produksi merupakan bagian integral di dalam sistem manufaktur. Artikel ini menyelesaikan permasalahan penjadwalan flow shop dengan fungsi obyektif total flow time. Dalam penjadwalan, total flow time menghasilkan konsumsi yang stabil terhadap sumber daya, perputaran job yang cepat serta meminimalkan work in process inventory. Permasalahan penjadwalan flow shop tergolong pada permasalahan optimasi kombinatorial yang merupakan NP-hard. Saat ini, penggunaan algoritma metaheuristik banyak digunakan untuk memecahkan kasus optimasi kombinatorial, termasuk penjadwalan flow shop. Salah satu yang memiliki performa yang baik adalah Algoritma Differential Evolution. Untuk meningkatkan kualitas solusinya, Algoritma Differential Evolution akan ditambahkan dengan prosedur local search yang dinamakan Hybrid Differential Evolution. Untuk mengetahui performa dari algoritma tersebut, dilakukan pengujian menggunakan data penjadwalan flow shop yang ada pada OR-Library. Performa Hybrid Differential Evolution akan dibandingkan dengan algoritma lain. Hasil pengujian menunjukkan bahwa Hybrid Differential Evolution memberikan performa yang lebih baik dibandingkan dengan algoritma lain.
Pengaruh Vaporasi Bahan Bakar Pertamax Terhadap Performa Sepeda Motor Dibandingkan dengan Pemanasan Biasa
Authors: Fajariansyah Andre , Fahruddin A'rasy , Bukhori Ahmad
Published: March 2017

Vaporasi bahan bakar adalah sistem penguapan bahan bakar, yaitu bahan bakar diuapkan menjadi gas dengan bantuan panas dari exhaust manifold. Vaporasi dari gas bahan bakar pertamax ini sangat efektif digunakan  untuk menghemat bahan bakar pada kendaraan bermotor. Prinsip kerja dari sistem ini adalah dengan memanfaatkan panas knalpot untuk memudahkan penguapan bahan bakar menggunakan pipa preheater yang ditempel di exhaust manifold. Bahan bakar yang telah panas kemudian masuk ke tabung vaporasi dan dihisap menuju intake manifold. Pada penelitian ini sistem vaporasi bahan bakar dibandingkan dengan sistem pemanas bahan bakar biasa. Hasil penelitian menunjukkan bahwa sistem vaporasi bahan bakar lebih baik dari mesin standar maupun sistem pemanasan bahan bakar biasa dari segi daya maupun efisiensi. Dan sistem pemanasan bahan bakar menghasilkan performa yang lebih baik dari mesin standar. Peningkatan daya dengan sistem vaporasi mencapai 13,2% sedangkan sistem penguapan biasa mencapai 8,8% dibandingkan mesin standar.
Karakterisasi Sensor Kapasitif Untuk Penentuan Level Aquades
Authors: Cahyono Bowo Eko , Misto Misto , Hasanah Faridatul
Published: March 2017

Kapasitor pelat sejajar adalah suatu komponen elektronika yang terdiri dari dua buah pelat penghantar sejajar yang disekat satu sama lain dengan suatu bahan dielektrik. Tujuan dari penelitian ini adalah mencari hubungan perubahan nilai kapasitansi terhadap kenaikan volume aquades dengan menggunkan metode kapasitif. Metode kapasitif memanfaatkan rangkaian sensor kapasitif yang dihubungkan dengan osiloskop untuk mengetahui tegangan masukan dan tegangan keluaran dan selanjutnya digunakan untuk menentukan nilai kapasitansi. Bahan yang digunakan dalam penelitian adalah aquades, dengan volume aquades yang digunakan divariasikan dari 18 mL sampai 180 mL. Hasil penelitian menunjukkan bahwa semakin meningkat volume aquades maka semakin besar nilai kapasitansi. Tetapi data hasil eksperimen menunjukkan bahwa ada beberapa hasil yang tidak konsisten yaitu meskipun volume aquades dinaikkan tidak menyebabkan kenaikan nilai kapasitansi. Hal ini terjadi pada kenaikan volume dari 72 mL ke 90 mL, kenaikan volume 108 mL ke 126 mL dan juga kenaikan volume aquades dari 144 mL ke 162 mL. Hubungan linieritas antara nilai kapasitansi dan level aquades dinyatakan dengan persamaan linier y = 0,0913x dengan koefisien linieritas R2 = 0,9106.
Rekayasa Desain dan Analisis Struktur perangkat dasar laut Ocean Bottom Unit (OBU) untuk INA – TEWS
Authors: Nugroho Wibowo Harso , Purnomo1 Nanang J. H. , Ivano Ogi , Handoyo S
Published: March 2017

This paper briefly describes the design and analysis of the structure of ocean bottom units (OBU) as a pair of surface buoys to detect tsunami early. This engineering work such as any other marine construction is based on naval architecture. The design concept OBU is firstly made then the stability calculation is conducted, finally the structural strength is calculated for load case of hydrostatic and impact as the OBU landed on approximately 2000m of ocean depths.
Wskaźnik niepełnosprawności głosowej – efektywność i korelacja pomiędzy cechami fizycznymi, funkcjonalnymi oraz emocjonalnymi a zaburzeniami głosu
Authors: Scech Marcin
Published: March 2017

Zaburzenia głosu są powszechnym zjawiskiem wśród osób pracujących w środowiskach narażonych na nadmierne używanie mowy jako narzędzia pracy. Brak wcześniejszego szkolenia z zakresu prawidłowej impostacji oraz fonacji powoduje, że kłopoty z głosem są obecne w dużej części społeczeństwa. W odpowiednim ropoznaniu powodów powstawania zaburzeń głosu pomaga współczynnik niepełnosprawności głosowej czyli Voice Handicap Index (VHI). Jako narzędzie wielokrotnie sprawdzone, pozwala nie tylko na samoocenę własnego głosu, ale również jest pomocne podczas weryfikacji efektów rehabilitacji głosu.
Propranolol jako skuteczna metoda leczenia nieoperacyjnych naczyniaków okołoocznych u dzieci
Authors: Babiak-Choroszczak Lidia , Giżewska-Kacprzak Kaja , Puchalska-Niedbał Lidia , Walecka Anna , Gawrych Elżbieta
Published: March 2017

Wstęp: Naczyniaki wczesnodziecięce w lokalizacji okołoocznej to poważny problem kliniczny. Nieleczone mogą prowadzić do poważnych konsekwencji, stwarzając zagrożenie dla prawidłowego rozwoju wzroku. Z uwagi na trudną lokalizację bywają nieoperacyjne, dlatego niezbędne jest małoinwazyjne leczenie oszczędzające oko. Celem pracy była ocena skuteczności leczenia propranololem nieoperacyjnych naczyniaków okolicy oczodołu u dzieci.Materiał i metody: Do badania włączono 17 dzieci z naczyniakami górnej i dolnej powieki oraz kąta wewnętrznego powiek. Pacjentów poddano szczegółowemu badaniu okulistycznemu. Guzy naczyniowe znacząco wpływały na prawidłowy ruch powiek, powodując w większości przypadków opadanie powieki. Ponadto zdiagnozowano przypadki astygmatyzmu anizometrycznego oraz wytrzeszcz. Pacjenci zostali zakwalifikowani do terapii propranololem i szczegółowo ocenieni po zakończeniu leczenia.Wyniki: We wszystkich opisanych przypadkach od pierwszych dni stosowania leku zaobserwowano rozjaśnienie powierzchni guza oraz zmniejszenie jego napięcia. U 90% pacjentów doszło do całkowitej inwolucji. W 5 przypadkach pozostało delikatne przebarwienie i zgrubienie skóry. U wszystkich dzieci doszło do znaczącej poprawy w zakresie funkcji narządu wzroku. Stwierdzono 86% redukcję astygmatyzmu w przypadkach, gdy był on zdiagnozowany wyjściowo.Wnioski: Wczesna diagnoza i szybkie włączenie propranololu w leczeniu naczyniaków okolicy oczodołu u dzieci obniża ryzyko powikłań zagrażających prawidłowemu widzeniu. Pomiar redukcji astygmatyzmu może być przydatny w monitorowaniu terapii. Propranolol jest lekiem z wyboru w przypadku naczyniaków okołoocznych, uwzględniając jego skuteczność, szybkość działania i mały odsetek występowania objawów ubocznych.
Długotrwały efekt optycznego rozogniskowania na wzrost oka i refraktogenezę
Authors: Tarutta Elena , Khodzhabekyan Narine , Filinova Oksana , Milash Sergei , Kruzhkova Galina
Published: March 2017

Wstęp: Celem pracy było zbadanie wpływu obuocznego i zmieniającego się jednoocznego stałego rozogniskowania krótkowzrocznego wypisywanych okularów na formowanie początku i postępu krótkowzroczności u dzieci.Materiał i metody: 129 dzieci w wieku 5–12 lat podzielono na 4 grupy: 48 dzieciom w wieku 5–8 lat (grupa I) z emetropią i czynnikami ryzyka rozwoju krótkowzroczności wypisywano soczewki plusowe do ciągłego noszenia, aby wytworzyć krótkowzroczność 1,0 D. 46 dzieciom w wieku 7–11 lat (grupa II) z niską krótkowzrocznością od −0,75 do −2,25 D wypisywano 2 pary okularów do zmieniającego się stałego noszenia. Jedno oko korygowano do dali tak, aby otrzymać resztkową krótkowzroczność w okularach ok. 0,50 D, oko towarzyszące korygowano tak, aby otrzymać resztkową lub aby wytworzyć krótkowzroczność ok. 1,50 D. Dzieci zmieniały okulary każdego dnia. Dane kontrolne otrzymano od 15 dzieci w wieku 6–9 lat (I grupa kontrolna) z pseudokrótkowzrocznością i bez stosowania korekcji oraz od 20 dzieci z niską krótkowzrocznością w wieku 7–12 lat (II grupa kontrolna) noszących konwencjonalną korekcję okularową. Wykonywano autorefraktometrię przed i po cykloplegii oraz biometrię ultradźwiękową.Wyniki: U wszystkich pacjentów z grupy I po miesiącu i dłuż- szym okresie obserwacji odnotowano przesunięcie w kierunku nadwzroczności spowodowane ścieńczeniem soczewki i pogłę- bieniem komory przedniej. Średnica horyzontalna (HD) powiększyła się 3 razy bardziej niż długość osiowa (AL). Nie zaobserwowano przypadku wystąpienia krótkowzroczności w ciągu 9-letniego okresu obserwacji. Stabilną refrakcję trwającą dłużej niż 4 -letni okres obserwacji miało 36 (81,8%) dzieci z grupy II. Stwierdzono nieznamienny wzrost AL i znamienny wzrost HD. W ciągu 3 -letniego okresu obserwacji w obu grupach kontrolnych AL wzrastał znamiennie, podczas gdy HD wykazywał wzrost niezamienny.Wnioski: Stałe niskie rozogniskowanie krótkowzroczne obrazu w okularach obuocznych hamuje wzrost oka i przesuwa refrakcję w kierunku krótkowzroczności u dzieci z niską nadwzroczno- ścią, emetropią i niską krótkowzrocznością. Metoda zmieniania jednoocznego niskiego roogniskowania hamuje postęp krótkowzroczności w 81,8% u dzieci z niską krótkowzrocznością przez 4 lata i w 66% przez 7 lat.
Autoimmunologiczny zespół indukowany przez adiuwanty (ASIA)
Authors: Stolarczyk Jędrzej , Kubiś Marek , Brzosko Marek
Published: March 2017

Dotychczas opisano wiele przypadków pojawienia się autoprzeciwciał i objawów chorobowych po ekspozycji na adiuwanty, nie tylko w kontekście wszczepienia silikonowych implantów piersi, ale również jako bardzo rzadko występujące odczyny poszczepienne, zespół wojny w Zatoce Perskiej (Gulf war syndrome) czy zespół makrofagowego zapalenia mięśniowo-powięziowego. Grupę chorób, których objawy wystąpiły po tego typu ekspozycji, nazwano autoimmunologicznym zespołem indukowanym przez adiuwanty (autoimmune/inflammatory syndrome induced by adjuvants – ASIA). Do adiuwantów, oprócz silikonowych implantów, zalicza się krzem, skwalen i glin, a także składniki pigmentów stosowanych do wykonywania tatuaży itp. Analizując piśmiennictwo odnoszące się do wpływu adiuwantów na rozwój chorób autoimmunologicznych, nasuwa się wniosek, że oprócz długotrwałej ekspozycji na silikon konieczne jest również współistnienie innych czynników, takich jak predyspozycja genetyczna czy wpływ czynników środowiskowych. Metaanalizy jednoznacznie nie potwierdzają zwiększenia ryzyka wystąpienia choroby autoimmunologicznej po wszczepieniu silikonowych implantów piersi lub wykonaniu tatuażu, ale możliwe jest zwiększenie predyspozycji do ich wystąpienia w pewnej grupie badanych pacjentów. W populacji ogólnej pozytywny wpływ stosowanych szczepień jest znaczący, a ryzyko wystąpienia poważnych odczynów poszczepiennych jest nieporównywalnie mniejsze niż ryzyko zachorowania na daną jednostkę chorobową i wystąpienia jej powikłań, również u chorych z rozpoznanymi chorobami reumatycznymi. Ze względu na niejednorodność wyników dotychczasowych badań oraz trudności w diagnostyce i rozpoznawaniu ASIA, konieczne będzie prowadzenie dalszych badań na temat wpływu adiuwantów na rozwój chorób autoimmunologicznych oraz dopracowanie kryteriów ASIA, które pozwalają obecnie na zbyt łatwe rozpoznawanie tego zespołu.
Ograniczenia funkcjonalne związane z dolegliwościami bólowymi odcinka lędźwiowo -krzyżowego kręgosłupa wśród kobiet ciężarnych
Authors: Brylewska-Pinda Magdalena , Kemicer-Chmielewska Ewa , Pierzak-Sominka Joanna , Mosiejczuk Hanna
Published: March 2017

Wstęp: Bóle dolnego odcinka kręgosłupa dotyczą większości kobiet w ciąży. Na skutek dolegliwości bólowych często pojawiają się ograniczenia funkcjonalne różnego stopnia sprawiające kłopot przy wykonywaniu wielu codziennych czynności. Celem pracy była ocena stopnia dolegliwości bólowych odcinka lędźwiowo-krzyżowego kręgosłupa oraz określenie zależności badanych ograniczeń od zmiennych kontrolowanych.Materiał i metody: Badanie przeprowadzono na terenie miasta Szczecina wśród 81 kobiet ciężarnych. Posłużono się standaryzowanym kwestionariuszem ankiety Oswestry (The Oswestry Low Back Pain Disability Questionnaire). Do weryfikacji statystycznej otrzymanych wyników badań wykorzystano test niezależności χ². Przyjęto poziom istotności p < 0,05.Wyniki: U większości kobiet będących po raz drugi w ciąży (n = 38) stwierdzono mierną niepełnosprawność. Zależność pomiędzy stopniem niepełnosprawności a kolejnością ciąż była statystycznie istotna (χ² = 40,457; p = 0,0000000085).Wnioski: U większości kobiet ciężarnych zaobserwowano ograniczenia funkcjonalne spowodowane dolegliwościami bólowymi odcinka lędźwiowo-krzyżowego kręgosłupa w stopnie miernym. Stopień ograniczeń funkcjonalnych zależny jest od trymestru ciąży i kolejności ciąż.
Ochrona przed stresem oksydacyjnym w męskim układzie płciowym
Authors: Marchlewicz Mariola , Szypulska-Koziarska Dagmara , Grzegrzółka Adam , Kruk Joanna , Duchnik Ewa , Wiszniewska Barbara
Published: March 2017

Reaktywne formy tlenu (RFT) pełnią w męskim układzie płciowym ważne funkcje fizjologiczne, m.in. w sygnalizacji komórkowej, w procesach spermatogenezy oraz najądrzowego dojrzewania plemników. Pod wpływem różnych czynników, np. środowiskowych, dochodzić może do zaburzenia równowagi oksydoredukcyjnej, czyli stresu oksydacyjnego. Prowadzi to do ekspozycji komórek na toksyczne działanie wielu utleniaczy, takich jak: O• ⁻₂, O₃, H₂O₂, • OH. Źródłem RFT mogą być plemniki, które jednocześnie ze względu na skład błon cytoplazmatycznych oraz dużą zawartość mitochondriów są wyjątkowo podatne na uszkodzenia peroksydacyjne. Stres oksydacyjny może uszkadzać ich błony i zawarty w nich DNA, hamować ruchliwość plemników oraz zmniejszać ich zdolność do zapłodnienia. Ten podwójny efekt działania RFT potwierdza szczególną rolę antyoksydantów enzymatycznych (m.in. SOD, CAT, GPX) i nieenzymatycznych (m.in. GSH, witaminy A, E, C, transferyny) odpowiedzialnych za utrzymanie odpowiedniego stężenia RFT w męskim układzie płciowym.
Jakość i dostępność opieki dla osób z zaburzeniami psychicznymi – opinie świadczeniodawców
Authors: Bażydło Marta , Karakiewicz Beata
Published: March 2017

Wstęp: Celem pracy było poznanie opinii świadczeniodawców opieki psychiatrycznej na temat jakości udzielanych usług.Materiał i metody: Materiał stanowiły opinie przedstawicieli placówek opieki psychiatrycznej na temat jakości udzielanych usług. Do badania włączono placówki z województwa zachodniopomorskiego. Wybraną metodą badawczą był sondaż diagnostyczny. W placówkach znajdujących się na terenie Szczecina przeprowadzono wywiad wspierany kwestionariuszem ankiety. W pozostałych placówkach przeprowadzono ankietę, a kwestionariusz wysłano pocztą po uprzedniej rozmowie telefonicznej. W badaniu posłużono się autorskim kwestionariuszem, który został skonstruowany w oparciu o kategorie jakości wyróż- nione przez Maxwella.Wyniki: We wszystkich kategoriach jakości najczęściej wskazywane oceny to odpowiedź „wysoka” i „średnia”. Odpowiedź „niska” była wskazywana niezwykle rzadko. Najwyżej oceniona kategoria jakości to sprawiedliwość w dostępie do usług. Aż 93,3% pytanych przyznało tej kategorii najwyższą ocenę, a 6,7% oceniło jej poziom jako średni. Druga najlepiej oceniona kategoria to kompetencje personelu. Aż 80,0% przedstawicieli placówek oceniło kompetencje personelu jako wysokie. Trzecia spośród najwyżej ocenionych kategorii jakości to skuteczność usług, czyli świadczenie usług zgodnie z aktualnymi wymaganiami wiedzy i aktualnymi doniesieniami nauki. Aż 76,7% pytanych oceniło skuteczność podejmowanych przez siebie świadczeń jako wysoką. Z kolei najniżej ocenione kategorie jakości to dostosowanie budynku do potrzeb pacjentów oraz bezpieczeństwo procedur.Wnioski: 1. Przedstawiciele placówek opieki psychiatrycznej wysoko oceniają jakość usług świadczonych przez reprezentowane przez siebie placówki. 2. Najwyżej oceniane kategorie jakości to sprawiedliwość w dostępie do usług, kompetencje personelu oraz skuteczność usług. 3. Najniżej oceniane kategorie jakości to dostosowanie budynku do potrzeb pacjentów oraz bezpieczeństwo procedur.
A Systematic Investigation of Factors Affecting the Formation of Zinc Sulfide (ZnS)
Authors: Graham A. J. , Singleton M. A. , Sorbie K. S. , Collins Ian R.
Published: March 2017

Work was undertaken to systematically investigate the factors that affect the formation of zinc sulfide (ZnS) in an aqueous system. Experiments were performed at a series of temperatures from room temperature up to 90°C, at a range of initial pH values and in two brine systems. The effect of pH was examined further by changing the salt from Na2S·9H2O to NaSH·xH2O, therefore changing the initial sulfide source from S2– to HS–, as part of an ongoing method-development strategy.

The formation of ZnS was achieved by the equivolume mixing of two preheated bottles, which contained aqueous “H2S” and zinc ions, respectively. Having pH adjusted the zinc brine to values calculated by an in-house thermodynamic model, the brines were preheated to the required temperature and mixed. Aliquots were removed at 2, 4, and 24 hours to perform elemental analysis by inductively coupled plasma optical emission spectrometry (ICP-OES), and pH measurements were performed on all samples after they had returned to room temperature. In addition, particle-size analysis and environmental scanning electron microscopy (ESEM) examination of the resulting precipitate were also performed for a subset of the samples prepared.

The reaction between zinc ions and aqueous “H2S” was quantitative at all temperatures up to 90°C and in both brines. The final pH values of the supernatant were independent of the zinc brine pH, and instead were dependent on the molar ratio of zinc and sulfide ions. With a high pH, sulfide-dominated, and a low pH, zinc-dominated, plateau regions were seen with a sharp inflection between the two. As a consequence, reaching field-representative pH values was seen to be extremely difficult while retaining the ability to alter the relative concentrations of the reacting ions. Altering the sulfide source yielded the same trend, although with different absolute values. These observations have been rationalized with reference to the thermodynamic constants governing the reaction through scale-prediction modeling.

The work presented here provides a greater understanding of the factors governing the formation of ZnS scale and the considerations required for more industrially relevant formation and inhibition experiments in the future.
A Direct Overparameterize and Optimize Method for Stratigraphically Consistent Assisted History Matching of Object-Based Geomodels: Algorithm and Field Application
Authors: Alpak Faruk O. , Jennings James W. , Gelderblom Paul , Chen Chaohui , Gao Guohua , Du Kuifu
Published: March 2017

Object-based static models are typically constructed for stratigraphically complex reservoirs. In this approach, the stratigraphic architecture is represented by use of distinct objects with specific geometric attributes and petrophysical characteristics. It is a major challenge to condition such models to production data while simultaneously maintaining the geologic realism and static conditioning.

A novel work flow is developed for the assisted history matching (AHM) of object-based geomodels where the uncertain object locations and attributes are directly modified without resorting to (post-geomodeling) reparameterization techniques. It contains an object-modeling algorithm for channels and levees that provides direct access to the preraster geomodeling parameters for individual object locations and attributes. These parameters are gradually modified subject to physical constraints to achieve a history match. A fully integrated protocol is used in this process that automatically couples the static modeling algorithm with the reservoir simulator. The resulting work flow is moderated by a massively parallel and highly efficient iterative data-integration algorithm. In the AHM work flow, static and dynamic conditioning operations are respectively driven by separate objective functions and are performed at the iteration level in a sequential fashion. The static-conditioning step may add and remove objects in the geomodel, which changes the number of active AHM parameters over the course of the iterative search. The work flow handles such operations with minimal impact on the robustness of the search.

A potential application of the direct AHM work flow for object-based geomodels is the identification of locations and attributes of channels in deepwater turbidite reservoirs, where the channels are typically below the resolution of the seismic data; the well spacing is typically larger than the characteristic object dimension, yet the production data exhibit strong sensitivity to channel connectivity. The concept of gradually adjusting the channel locations with the information in the production data (while maintaining static conditioning) is demonstrated on a real data set for a deepwater channelized-turbidite reservoir. The models proposed by the new AHM work flow not only improve the difficult-to-history-match injected-gas-breakthrough profiles but also provide geologically based explanations for them, taking into account the channel connectivity. The proposed AHM work flow ensures consistency across static and dynamic models by integrating multidisciplinary data with an easily auditable and replicable capability.
Method to Improve Human Resource Allocation in Project Teams Using Simulation: An Application to a Well Engineering Team
Authors: Lira G. A. , Pedrassa M.. , Veiga I. G. , Torres C. E. , Santos A. S.
Published: March 2017

Human Resources allocation is a crucial factor for success in multi-project companies. It should consider the quantity of professionals needed to develop the project and the amount of time these professionals can dedicate to it. Companies where the core business is engineering design, software design or research and development projects, usually need a variety of specialists and the allocation of these workers on the projects can be done by a simulation of the process aiming to obtain better system performance. This work makes an analysis of sizing and allocation of human resources on design processes, proposing a simulation based method to improve it. An application to onshore oil well design process for a petroleum company was made, generating a model that represents the amount of professionals needed according to a given demand. After that, some scenarios were simulated aiming to improve the system performance metrics. Through the proposed method, the process was analyzed, identifying some bottlenecks and improvement points related to downsizing and deadline accomplishment. The simulated scenarios have shown that an organization modification through centralization of well engineering offices could reach these goals.
Effect of Pressure Depletion on Stress Field and Casing Load Alteration in Mature Fields: A Case Study
Authors: Zhang Peng , Zhang Shang , Hu Ningjie , Zhang Feifei , Makhmoor Felor , Carlos Sandoval Juan
Published: March 2017

Long-term oil production can lead to pressure depletion in mature fields, which can cause noticeable wellbore impairments, particularly in soft formations. This paper presents a case study that was conducted with the application of mature field data from Latin America to identify stress field and casing load alteration caused by long-term production.

A stochastic reservoir model was built integrating field geological, geophysical, and petrophysical analyses. The model displayed facies-controlled petrophysical properties distribution. A simulation model was then developed to provide reservoir pressure profiles. The overburden displacements induced by pressure depletion were calculated using Geertsma’s analytical method based on the poroelasticity theory. Then, the strain and stress fields in the formation were determined following a finite difference scheme. Following, casing integrity and wellbore stability analyses were performed.

Reservoir simulation results show an average pressure drop of approximately 800 psi from initial field pressure. Pressure profiles were used to calculate displacements and stresses in overburden rocks, and displacements were incorporated in casing design software. Results show increased compressional stress along the casing string, which can lead to casing and cement failure. Moreover, the induced stresses caused by pressure drop alter the in-situ stress fields in the formation. The result is stress-cloud movement along the wellbore toward the failure envelope. Corresponding precaution is necessary to help mitigate risks associated with long-term oil production in this field.

This paper provides a methodology for predicting production-induced wellbore integrity problems and suggestions for helping improve safety management and reducing environmental risks associated with mature field development.
Comparative Analysis of Two-Phase Flow in Porous Media in Two Different Configurations of Wells Through 3D Numerical Solution Using OpenFOAM
Authors: Soares Vivas Cláudio , Fernando Britto Antonio , da Cunha Lima Ivan C. , da Cunha Lima André T. , de Almeida Murilo P.
Published: March 2017

With the advance of high-performance computing (HPC) the use of CFD software has become common in research in Fluid Dynamics, either to obtain the numerical solutions of differential equations that model the various systems or the dynamics for viewing and analyzing data obtained in the simulations. In this work we look to benchmarking between two distinct two-phase flows from two geometrically different wells through the analysis of their respective accumulated volumes of non-wetting fluid in the outflow. Three simulations were performed, for each set of wells, both during the same interval of time and under the same pressure gradient. The OpenFOAM software and Finite Volume Method for solving differential equations were used.
Influence of Well Control Parameters in the Development of Petroleum Fields Under Uncertainties
Authors: Santos Daniel Rodrigues , Schiozer Denis José
Published: March 2017

In the development of oil fields, many parameters have to be selected in optimization procedures, demanding large computational effort, especially when uncertainties are considered. Therefore, it is common to separate design variables (G1) and well control variables (G2) optimization in a hierarchical process, but this may yield suboptimal results. We propose a well control analysis under uncertainties to verify whether G2 can be optimized separately in the development phase of petroleum fields. We also investigate the impact of G2 optimization on economic returns when platforms limit the production and for more pessimistic production costs. We perform reactive and proactive G2 optimization under uncertainties on a Benchmark Model (UNISIM-I-D, based on Namorado field) in three cases. In Case I, we use previously optimized strategies for G1, while G2 were controlled in a simplified way considering geological and economic uncertainties. In Case II we investigate the G2 optimization based on expected monetary value (EMV) for a restricted platform. Case III adopts the same restriction of Case II, but considers a pessimistic economic scenario. We consider five procedures for G2 optimization: (P1) longterm bottom-hole pressure control; (P2) short-term rates control; (P4) long-term rates control; (P4) well shut-in time control; and (P5) a combination of these procedures. In Case I, the EMV low percentage increase after G2 optimization indicates that a hierarchical process can be used in similar problems. Yet, G2 should be optimized during the lifetime of the field to increase EMV without additional cost. Depending on the representative model (RM) that best characterizes the field, there are potential further gains of almost 200 million USD for one of the scenarios studied. We achieved an increase of EMV around 8% for Case II. This suggests that G2 have a greater economic return when the platform restricts the production and injection for the field and G1 were not previously optimized. Case III showed even higher EMV gain (34%) indicating the importance of considering the economic scenario when defining the G2 strategy for the field. To reduce the search space in optimization problems, conventional techniques focus on optimizing design variables, underestimating the influence of well control management on G1. Moreover, some works do not include uncertainties and operational constraints. The results of this work indicate that G1 and G2 can be optimized hierarchically for a situation in which platforms do not constraint production or injection (Case I), since G2 variables have lower influence. This conclusion is not valid for restricted platforms and a pessimistic economic scenario (as in Case II and III) where G2 have higher influence in the results.
Practical Management in Mature Field Operations
Authors: Hirschfeldt Clemente Marcelo , Bertomeu Fernando Diego , Lobato-Barradas Gerardo
Published: March 2017

An operation model for mature field not only should be used during a world oil price crisis, but also it should be incorporated as a best practice during the life of the oil field, consequently, in mature field projects it is always possible both to improve its profitability indicators and to increase its hydrocarbons production. One of the most important challenges is to incorporate these actions as a mature field management culture by supporting existing facilities operations and field elements using best practices focused on processes, human resource skills and technological elements.

Operators have a great opportunity concentrated in these key aspects to optimize results by reduction and optimization of costs and improvement of operations.

The objective of this paper is to provide a practical guide to be considered during the field operation and management of mature asset, addressing actions to maximize the operation efficiency, maximize the hydrocarbon recovery factor and to optimize costs and resources.

It describes an integrated operations process for low profitability projects/fields, like mature fields and marginal fields, summarizing best practices to identify opportunities in existing operations.

The paper also describes how to find opportunities by clear understanding the relationship among key processes such as:Reservoir Management and Surveillance,Water Management, Waterflooding and EOR,Drilling, Completion, and Production Engineering,Artificial Lift Management,Efficiency and Cost Control.Suppliers and service company's management

These best practices addressing organized processes, human resource skills and technology elements are described clearly and they are presented as tools for easy implementation. Case studies in Mexico and Argentina are shown, along with management models for implementing, surveilling and maintaining mature fields which resulted in lower operation costs and a sustained oil production increase.
An Alert-Based Monitoring System to Evaluate a Water Injection Pilot in the Shushufindi Field, Ecuador
Authors: Paredes Luis , Fonseca Claudio , Meza David , Torres Camilo , Henson Richard , Withney Patricio , Lafournere Jean Paul , Ponce Gustavo
Published: March 2017

Secondary recovery by water injection is one of the most popular methods to increase reservoir pressure and sweep efficiency in the industry. It is a cost effective technology in reservoirs such as Shushufindi field, where water, energy and sink points are easily available. This pilot aims to provide proof of concept of water injection in mature Ecuadorian fields.

The water injection pilot project was carried out in the central north area of the field, in the lower U reservoir, selected as the target injection horizon due to pressure depletion. The injection started in December 2014 in SHS-246D and SHS-244D and then in 2015 two more injector wells were set up, SHS-247 & SHS-003. These wells are located in a 125 acres area, based on inverted five spot pattern.

Secondary projects around the world have shown that the success of any water injection project is based on an exhaustive monitoring and surveillance process, along with using the many analysis tools and plots available.

Shushufindi, however, needed a specific tailored toolset that fits the surface operating conditions, one that is able to monitor the variables required to understand the local reservoir hydraulic behavior, minimizes issues in the injection cycle, and provides quality data for the continuous improvement of the water injection pilot. In order to achieve this objective, some variables were selected and recorded in a group of theoretical plots. This was achieved by developing a series of workflows on a production management software platform, centered on an alert system to rapidly identify changes in the monitored injection variables and to respond if needed.

This monitoring system allows a quick identification of well plugging issues in injector wells through the use of Hall plots, it also tracks the water quality at different points in the water processing plant allowing adjustments to made to the process to improve the water quality if needed, provides information for reservoir characterization monitoring, Voidage Replacement Ratio (VRR), and determines the water injection response in producer wells by monitoring the production parameters.
Enhancing Reservoir Understanding in Mature Fields: Adjoint-State Method Applied to a Semi-Synthetic Model
Authors: Awofodu D. D. , Ganzer L.. , Almuallim H..
Published: March 2017

Model validation using available history data demands that the model reflects relevant behaviour occurring in the subsurface. Reservoir models lacking in proper modelling of essential reservoir behaviour are poor representatives of reality. Usually, calibrating these models to history data require excessive use of parameter fudging to achieve meaningful match results. To combat this issue, an efficient approach to improve reservoir understanding is presented that investigates hidden reservoir behaviour at field, region and well level.

The model screening approach uses static grid properties to explore unmatchable models for hidden reservoir behaviour. Permeability and/or porosity is defined as an input for the minimization problem with preset uncertainty limits ranging from zero to values greater than the default maximum values. The adjoint-state method is employed to condition simulation models to observation data. Unrealistic match results are realized at this stage which cannot be used for performance forecasting. Logical interpretation are generated for the extreme property updates. Feedback from interpretations are then used to enhance reservoir understanding. The PUNQ-S3 model is used to test proposed screening methodology.

A variant of the adjoint-state method executed in an unrestrained manner proved its capability to reveal hidden reservoir behaviour. A handful of patterns that draws attention to hidden reservoir behaviour were observed in permeability and/or porosity distribution. In the case of a hidden fault, the permeability distribution around influenced wells experiences a sharp contrasting change; the high permeability region seeks more oil while the low permeability region constrains oil production. Also, in the case of a hidden aquifer, we observed an extreme vertical porosity and permeability update travelling down through all layers into the oil-water contact zone. Hidden channels are represented as high permeability streaks connecting affected wells. So far, the model screening approach suffers from one limitation – an inability to differentiate between a reservoir boundary and a fault close to the boundary.

To guarantee that geological consistency is not sacrificed at the expense of history matching, local or global updates made to the starting model are restricted to true model variogram. The most crucial finding is that the production history must account for the physical mechanisms occurring in the representative reservoir. On the contrary, noisy production data or errors in field measurements limit the effectiveness of the adjoint-state method to provide insights on hidden reservoir behaviour.
Evaluation of Novel Products Applicable to Enhanced Oil Recovery
Authors: Legarto Maria Leticia , Vega Isabel , Robledo Dario , Bordenave Veronica
Published: March 2017

Chemical Enhanced Oil Recovery (EOR) technologies include polymer, alkaline, surfactant injection and any combination of those. One of the main chemical EOR process is surfactant flooding whose key mechanism is the interfacial tension (IFT) reduction between oil and the displacing fluid. The IFT reduction is associated to the increase of capillary number, which is the dimensionless ratio of viscous-to-local capillary forces. Therefore, as IFT is reduced through the addition of surfactants, the ultimate oil recovery is enhanced.

The purpose of this work is the design of a systematic methodology to evaluate already existing products as well as new ones that are typically used for wells cleaning or damage removal, to be applied for Chemical Enhanced Oil Recovery. Solutions at different concentrations were prepared in synthetic brine. The behavior of these solutions at room and reservoir temperatures was observed. Quick Scans (qualitative method) were performed to evaluate the decrease of the IFT with two crude oils from Argentina basin; and the IFT was measured with a Spinning Drop Tensiometer.

According to some previous consulted literature, enzymatic, terpenic and surfactant products should present an intermediate recovery between a polymer flooding and ASP / SP processes. To understand how this recovery works, flow tests using 80 microns glass beads were carried out. These results led to an approximated recovery factor applying flooding of these chemicals.
Efficacy of Bisulfite Ions as an Oxygen Scavenger in Monoethylene Glycol (At Least 20 wt%)/Water Mixtures
Authors: Salasi Mobin , Pojtanabuntoeng Thunyaluk , Wong Sindee , Lehmann Marc
Published: March 2017

This study investigates the oxygen-scavenging behavior of bisulfite ions in monoethylene glycol (MEG)/water mixtures at concentrations commonly found in gas-transportation pipelines. Temperatures and pH values were varied. The influence of transition-metal (TM) ions to catalyze the bisulfite oxygen scavenging was studied. Experimental results indicate that MEG significantly inhibits bisulfite oxygen removal, which is hindered at low pH values and, to some extent, temperature. TMs can accelerate the oxygen-scavenging reaction in pH-unadjusted solutions, although the rate was still lower than that of the pH-adjusted solutions. The possible mechanism for such behavior and industrial implications are discussed.
Projeto InterAção: Responsabilidade Social e Meio Ambiente
Authors: Castro Ana Maria Rodrigues Costa de , Souza Aryane Cristina Gonçalves de , Castro Daniela Grijó de , Souza Nádia Dutra de
Published: March 2017

O “Projeto InterAção – Responsabilidade Social e Meio Ambiente” é um programa de extensão da Universidade Federal de Viçosa que tem como foco o fortalecimento da coleta seletiva em Viçosa. Criado em 2008, tem realizado desde então ações de implantação e consolidação da coleta seletiva em Viçosa, buscando sensibilizar a comunidade para a mudança nos comportamentos e atitudes e o fortalecimento das associações de catadores da cidade. Como resultado, verifica-se o aumento no número de locais que participam da coleta seletiva, bem como o aumento da sensibilização da comunidade. No entanto, falta investimento nesse setor por parte do poder público.
O princípio da indissociabilidade entre ensino, pesquisa e extensão como paradigma de uma universidade socialmente referenciada
Authors: Augusti Rudinei Barichello , Dalcin Larissa
Published: March 2017

Este texto destina-se a fazer uma análise do princípio da indissociabilidade entre ensino, pesquisa e extensão apontados como um paradigma de uma universidade socialmente referenciada, buscando neste sentido um diálogo crítico a partir do qual vem sendo constituída a universidade, suas possibilidades e limites. O mesmo descreve, analisa, sintetiza e está aberto à posteriores discussões. Primeiro, busca refletir a construção histórica da Universidade; em segundo, faz uma abordagem da Universidade enquanto campo epistêmico, situando o Ensino e a Pesquisa como indissociáveis tecendo a universidade a partir do elemento universalidade do saber e do conhecimento; em terceiro, discute e apresenta o princípio da indissociabilidade entre Ensino, Pesquisa e Extensão; por último, apresenta as abordagens legais, didáticas e metodológicas da indissociabilidade entre Ensino, Pesquisa e Extensão no cenário da Universidade de hoje.
Augmented hypertensive response during co‐administration of vasoconstrictive and antimuscarinic agents
Authors: Meng Lingzhong , Warner David
Published: March 2017

A patient presenting for a craniotomy developed severe hypertension during scalp infiltration of epinephrine‐containing local anaesthetic solution. The exaggerated arterial blood pressure response to epinephrine was attributed to glycopyrrolate administered 10 min earlier. Antimuscarinic agents impair the parasympathetic component of the baroreflex, the essential feedback mechanism in regulating blood pressure. Antimuscarinics also decrease the distensibility and increase the stiffness of major arteries, leading to an augmented response in blood pressure. The interaction between co‐administered sympathetic vasopressors and antimuscarinic agents has been largely overlooked. Vigilance for a hypertensive crisis is recommended during co‐administration because they could cause organ injury.