181,073 research outputs found
Physiological aspects of raffinose family oligosaccharides (RFOs) in plants: Protection against abiotic stress
No full textElSayed A, Rafudeen M, Golldack D. Physiological aspects of raffinose family oligosaccharides (RFOs) in plants: Protection against abiotic stress. Plant Biology. 2014;16(1):1-8
Experimental and numerical investigations of aerodynamic characteristics for wind turbine airfoil using multi-suction jets
No full textThe present work investigates the effects of multi-suction jets on the NACA 0012 airfoil's aerodynamic characteristics
at Reynolds number Re equal 0.54 × 105. Experiments and numerical simulations are carried out to this
purpose. The surface of the airfoil is equipped with multiple suction slots, and aerodynamic forces are measured
as a result. Numerical simulations are employed to illustrate the flow structures on both the modified and unmodified
airfoils. The study examines how the lift coefficient, drag coefficient, stall angle, and flow separation
are influenced by the location of the airfoil surface suction jets, suction pressure values, and the number of suction
slots. Additionally, the study investigates flow reattachments to identify the optimal control case. The results
demonstrated that the multiple suction jets along the airfoil blade's upper surface have the best lift coefficient increment
performance. In particular, the results showed that maximum improvements in lift coefficient, CL, is attained
as 480%, at a stall angle of attack (AOA) equal to 22° and flow speed of 8 m/s using numerical simulation
with the suction slot. The experimental results showed that lift coefficient improvements, CL, reached 55.7% using
suction holes at a stall AOA equal to 16° and a flow speed of 8 m/s. In addition, the CL, CD, CL/CD, and separation
flow are very sensitive to the suction jet location and the use of the multi-suction technique simultaneously
Digitally fabricated low cost housing: material, joint and prototype
No full textMotivated by the global housing deficit and limited natural resources, this study aims to utilize
digital fabrication technologies coupled with local sustainable materials in the quest for
alternative, adequate low-cost housing solutions for the less fortunate population, mainly in
developing countries.
The thesis is structured into two main parts: a theoretical and an empirical study. The theoretical
part identifies the research problem and lays the foundation of knowledge, as well as defines the
motivating questions, aim, objectives, scope, methodology and tools used throughout the thesis.
An overview of fundamental concepts of mechanisation, standardisation, prefabrication, mass
housing, and mass customisation is provided. Different types of prefabricated housing are
presented followed by a discussion of select architect-led and industry-led early precedents in
prefabrication. The theoretical part also includes an analysis of state-of-the-art built projects or
prototypes of digitally fabricated houses. Through this analysis, how these prototypes respond to
housing problems is addressed and an observation is made of how these built projects can be
categorised into main streams or different trends. After defining the potentials and limitations of
these precedents, a number of design criteria or design guidelines are proposed forming the basis
for the proposition of a housing system that addresses these drawbacks under the name “Housing
System 01”.
The second part of the thesis is a Design-Build-Evaluate empirical study in which the proposed
housing system combining concepts of complete off-site prefabrication with modular parametric
localised digital fabrication is outlined. Given the necessity of cost reductions, an integral joining
system (snap-fit) using an agricultural residue panel material is tested as the principal method for
the construction of wall assemblies. The study proves that by using integral joints, it is possible to
involve the end-user of the housing unit in the construction activities promoting the concept of
“Self-Build”, as the simplicity of the system allows for the participation of end-users with no
previous construction expertise thereby decreasing cost.
A set of mechanical tests are performed to characterise wheat straw panels and then snap-fit
joints are dimensioned within the elastic limits of this specific material. Three partial wall
assembly prototypes are built. One axial compression test is performed on one of the prototypes.
The tests show that the material and the joint system promise to provide a viable construction
system as an alternative low-cost housing solution. Further optimisation and more physical
structural testing are needed to address more complex forces and loading scenarios
Hydro-morphologic modelling for different calamitous scenarios in a mountain stream
No full textAnalysis of different scenarios is addressed for the Mallero river, a mountain stream in northern Italy. A town (Sondrio) is present at the downstream end of the river. Flood hazard for Sondrio can be related either to flood events with significant sediment transport (because the in-town reach is a preferential location for aggradation processes with resulting increase of the water elevation) or to dam-break events (in case of collapse of a major landslide at relatively short distance upstream). Therefore, the manuscript explores the use of hydro-morphologic modelling to assess the level of hazard related with the scenarios for flood with intense sediment transport and for landslide and following dam-break wave. For the first scenario, a past event (flood of 1987) is considered, that has been already object of previous investigations. Propagation of the flood wave and resulting river morphologic changes are modelled using the coupled Saint-Venant and Exner equations. For the second scenario, different models are combined in an integrated process chain: available estimations of the landslide volume and models for dam breaching are used to create inflow conditions in terms of water and sediment discharge into the river, then the wave propagation is modelled again using the shallow-water, one-dimensional approach. For both scenarios, the analysis is devoted to assessing if these waves could be able to transport a significant amount of sediments to Sondrio, maximum elevation of the water surface and characterization of the time scales for the events. The role of analyses such as that presented here for territorial management and protection is discussed
Analyzing the connectivity potential of landscape geomorphic systems: a radar remote sensing and GIS approach, Estufa Canyon, Texas, USA
No full textConnectivity is considered one of the fundamental aspects that influences the rate
of mass movement in the landscape. The connectivity aspect has been acknowledged
from various conceptual geomorphic frameworks. None of these provided a
developmental methodology for studying the connectivity of geomorphic systems,
especially at the scale of the fluvial system. The emphasis in this research is placed on
defining variables of the geomorphic systems that influence the connectivity potential of
these systems. The landscape gradient, which is extracted from the Digital Elevation
Model (DEM), and the surface roughness, which is extracted from radar images, are
used to analyze the connectivity potential of geomorphic systems in the landscape.
Integration of these variables produces a connectivity potential index of the various
geomorphic systems that compose the fluvial system. High values of the connectivity
potential index indicate high potential of the geomorphic system to transport mass
whereas the low values indicate low potential of the geomorphic system to transport
mass in the landscape. Using the mean values of the connectivity potential index, the geomorphic systems in the landscape can be classified into geomorphic systems of low
connectivity potential, geomorphic systems of intermediate connectivity potential and
geomorphic systems of high connectivity potential. In addition to the determination of
the relative connectivity potential of various geomorphic systems, the connectivity
potential index is used to analyze the system-wide connectivity.
The ratios between the connectivity potential index of the upstream geomorphic
systems and the connectivity potential index of the downstream geomorphic systems
define system-wide connectivity in the landscape. High ratios reflect the high potential
of the upstream geomorphic systems to transport mass in the downstream direction. Low
ratios indicate the influence of the downstream geomorphic systems in maximizing mass
movement in the upstream geomorphic systems. The presence of high and low ratios
suggests the presence of a high system-wide connectivity. As the ratio approaches unity,
mass movement is minimized in the landscape indicating low system-wide connectivity.
Applying the above approach to Estufa Canyon, Texas, illustrated that Estufa Canyon is
a dynamic fluvial system with high system-wide connectivity
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Stefaniella skuhravae Elsayed, new species
No full textStefaniella skuhravae Elsayed, new species Adult description. Color of freshly emerged individuals: head black, antennae light brown, thorax brown, wings transparent, legs light brown, upper and lower parts of abdomen light brown, lateral parts orange. Body length. 0.7 mm (n= 7) in males and 1.1 mm (n= 5) in females. Head (Fig. 24). Compound eyes with circular facets. Gap between eyes on vertex about 0.5-1.5 times as wide as facet. Palpi 2 –segmented, second segment elongated, nearly longer than the first. Antenna 2 + 9–10 flagellomeres; scape conical, pedicel rounded, flagellomeres barrel-shaped in both sexes; each with two connected rings of circumfila (Fig. 25); the apical two flagellomeres sometimes fused. Thorax.Wing (Fig. 26) length 0.6 mm (n= 7) in males and 1.0 mm (n= 5) in females. Vein R 5 joining C before its mid-length; C broken beyond the attachment point with R 5; M present; CuA simple. Tarsal claws (Fig. 27) toothed. Empodia as long as, or shorter than, claws. Abdomen, male. Tergites 1–7 rectangular, with a posterior row of strong, hyaline setae; tergites 2–7 with one pair of anterior, small, trichoid sensilla; tergite 8 very narrow, about 0.33 width of tergite 7, with median pair of trichoid sensilla. Sternites 1–7 with scattered setae, in addition to posterior row of strong hyaline setae; sternum 8 undifferentiated from the surrounding membranous tissue. Genitalia (Fig. 28): Gonocoxite slightly elongate, with setulose mediobasal lobe. Gonostylus 0.5 times as long as gonocoxite, arched, ending with a strong tooth. Cerci fused at base, forming one apically notched sclerite, setulose. Hypoproct entire, setulose, shorter than tips of cerci, with rounded tip. Parameres dorsally covered with dense tiny setae, and surrounding aedeagus. Aedeagus cylindrical, straight, slightly longer than parameres, with truncate tip. Female: (Fig. 29): Tergites 1–7 with 1–2 posterior rows of strong, hyaline, setae, and anterior trichoid sensilla; tergite 8 weakly sclerotized, about half width of tergite 7, divided into two sclerites. Sternites 2–7 with 1–2 posterior rows of hyaline setae. Ovipositor: segment 8 with lateral group of strong, curved, internally directed setae; membranous part rugose with papillae surrounded with tiny spines. Segment 9 (ovipositor trunk) with two sclerotized rods that widen posteriorly, forming weakly sclerotized triangular plate covered with tiny spines. Lateral plate bearing about 25 thick and strong setae. Aculeus straight, thick, tapered at apex, with two rows of tiny setae, every row consists of ~ 22 setae. Apical lamella rectangular and setose. Holotype. Female, Egypt, El-Amria district (30 ° 59 '54.00"N, 29 ° 49 '7.00"E), 4. VI. 2013, A. K. Elsayed reared from galls on male floral inflorescences of Atriplex halimus. Paratypes. All material from Egypt, El-Amria district, Alexandria, reared by A. K. Elsayed from galls on male floral inflorescences of A. halimus. 1 males, 12.VI. 2013; 1 male, 13.VI. 2013; 2 females, 14.VI. 2013; 2 females, 3 males, 16.VI. 2013; 4 males, 17.VI. 2013; 5 males, 2 females, 19.VI. 2013; 8 males, 20.VI. 2013; 1 female, 22.VI. 2013; 2 females, 24.VI. 2013. Distribution. Egypt (El-Amria district). Etymology. This species is named in honor of Mrs. Marcela Skuhravá, the Czech entomologist and expert on the family Cecidomyiidae (Diptera). Biology. Larvae of S. skuhravae induce small, slight swellings (Fig. 9 and 10) on male floral inflorescences of the salt marsh plant Atriplex halimus. The gall consists of a single chamber, and pupation takes place inside it. The pupal exuviae protrude from the emergence hole, and can be distinguished by their hyaline color. The galls were collected and the adults emerged from the end of May to October 2013. Remarks. The genus Stefaniella contains 9 species (Gagné & Jaschhof 2014). Dorchin & Freidberg (2008) revised all the species and found no significant differences between them in morphological characters. They concluded that study of the immature stages is needed, and molecular study will be useful to determine relationships between the species. They added that the currently the best characters for distinguishing species of Stefaniella are those of their galls. There are two known species of Stefaniella that induce galls on A. halimus: S. atriplicis Kieffer, 1898 and S. trinacriae De Stefani, 1900 (Dorchin & Freidberg 2008, Gagné & Jaschhof 2014). Stefaniella atriplicis induces small stem galls, each gall about 4–5 mm in diameter and multiple chambers (Skuhravá et al. 2007). Stefaniella trinacriae induces large galls on the stems, each gall about the size of a hazelnut and having multiple chambers. In contrast to the preceding species, S. skuhravae induces small galls on the male floral inflorescence, and each gall consists of only a single chamber. Therefore, we consider it to be a new species.Published as part of Elsayed, Ayman Khamis, Skuhravá, Marcela, Karam, Hedaya Hamza, Elminshawy, Abdelaziz & Al-Eryan, Mohamed Awad, 2015, New records and new species of gall midges (Diptera: Cecidomyiidae) developing on Chenopodiaceae in Egypt, pp. 105-115 in Zootaxa 3904 (1) on pages 112-114, DOI: 10.11646/zootaxa.3904.1.6, http://zenodo.org/record/23434
Primofavilla aegyptiaca Elsayed, new species
No full textPrimofavilla aegyptiaca Elsayed, new species Adult description. Color of freshly emerged females: head black, antennae brown, thorax dark brown, wings transparent, legs light brown, upper and lower parts of abdomen black, lateral parts red and covered with scales. Body length. 1.8 mm (n= 2) in female. Head (Fig. 19). Compound eyes with circular facets. Gap between eyes on vertex about 0-2 times as wide as facet. Palpi 2 -segmented, the second segment slender, elongated, slightly longer than the first. Antenna 2 + 10 - segmented; scape conical; pedicel rounded; flagellomeres barrel-shaped, each with two connected rings of circumfila, except the terminal flagellomere, with two sets of two connected rings of circumfila (Fig. 20). Thorax. Wing (Fig. 21) length about 1.5 mm (n= 2) in female; vein R 5 joining C at its mid-length; C broken beyond the junction point with R 5; M present; CuA simple. Tarsal claws (Fig. 22) curved and toothed. Empodia much shorter than claws, about as long as the small basal tooth. Female Abdomen. (Fig. 23): Tergites 1–7 rectangular, setulose, and with 1–2 posterior rows of strong setae; tergite 8 about 0.3 width of the tergite 7. Sternites 2–7 rectangular, setulose, with posterior row of hyaline setae. Ovipositor: segment 8 with lateral group of strong curved setae, the membranous part rugose with papillae surrounded with tiny spines. Lateral plate with ~ 26 strong, straight and thick setae. Aculeus curved and bare. Apical lamella oval, setose; the basal third of the dorsal margin covered with filiform short setae and the apical two thirds covered with short lanceolate setae. Holotype. Female, Egypt, Alexandria, El-Amria district (30 ° 59 '54.00"N, 29 ° 49 '7.00"E), 26.V. 2013, A. K. Elsayed, reared from leaf galls on leaves of Atriplex halimus. Paratypes. 1 female, 26.V. 2013, El-Amria district, Alexandria, reared by A. K. Elsayed from galls on leaves of Atriplex halimus. Distribution. Egypt, Alexandria, El-Amria district. Etymology. The name of that species is derived from Egypt. Biology. Larvae of P. aegyptiaca induce globular galls, 2-3 mm in diameter, on both surfaces of leaves (Fig. 8) of the salt marsh plant A. halimus. Each infested leaf has 2-6 galls, usually beyond the mid-rib. The galls were found in May and June 2013. The galls were collected and preserved in test tubes to rear the adult stage, but that method was not very successful, as only 2 females emerged and the pupation site was not determined. Another method was tested to rear the adults, the galls were collected and put in a plastic jar with soil at the bottom, but no adults emerged. Remarks. The three known species of Primofavilla, P. initialis Mamaev 1972, P. kaplini Fedotova 1991, and P. cystiphorae Fedotova 1991, are associated with Atriplex salina Siev., A. nana Parr-Sm., and A. tatarica L., respectively (Fedotova 1991 b, Gagné & Jaschhof 2014). The identification of Primofavilla species could be determined by the diagnostic morphological characters of the female ovipositor (Mamaev 1972, Fedotova 1991 b). The dorsal margin of the ovoid apical lobe of P. kaplini has only filiform setae, in contrast to P. aegyptiaca, P. cystiphorae and P. initialis, which have the filiform setae only on the basal third of the dorsal margin with the remaining setae either lanceolate (P. aegyptiaca and P. cystiphorae) or squamiform (P. initialis). Primofavilla aegyptiaca is closest to P. cystiphorae, but the former has dorsal and ventral sclerotized plates at the base of segment 9 of the female abdomen, while the latter does not. Primofavilla aegyptiaca also differs from P. cystiphorae in the distribution and number of strong setae on the lateral plate, which do not extend to the ventral side in P. aegyptiaca, unlike in P. cystiphorae. In addition to these differences, P. aegyptiaca has a bare saddle-like projection at the base of the aculeus. Therefore, P. aegyptiaca is considered to be a new species. Very similar galls were shown by De Stefani (1942) on the same host plant in Sicily, Italy, but the gall inducer was not identified, strongly suggesting the presence of P. aegyptiaca in Italy.Published as part of Elsayed, Ayman Khamis, Skuhravá, Marcela, Karam, Hedaya Hamza, Elminshawy, Abdelaziz & Al-Eryan, Mohamed Awad, 2015, New records and new species of gall midges (Diptera: Cecidomyiidae) developing on Chenopodiaceae in Egypt, pp. 105-115 in Zootaxa 3904 (1) on pages 111-112, DOI: 10.11646/zootaxa.3904.1.6, http://zenodo.org/record/23434
A variational constitutive model for soft biological tissues
No full textIn this paper, a fully variational constitutive model of soft biological tissues is formulated in the finite strain regime. The model includes Ogden-type hyperelasticity, finite viscosity, deviatoric and volumetric plasticity, rate and microinertia effects. Variational updates are obtained via time discretization and pre-minimization of a suitable objective function with respect to internal variables.
Genetic algorithms are used for model parameter identification due to their suitability for non-convex, high dimensional optimization
problems. The material behavior predicted by the model is compared to available tests on swine and human brain tissue. The ability of the model to predict a wide range of experimentally observed behavior, including hysteresis, cyclic softening, rate effects, and plastic deformation is demonstrated
- …
