The Military Revolution thesis posited by Michael Roberts and expanded upon by Geoffrey Parker places the trace italienne style of fortification of the early modern period as something that is a novel creation, borne out of the minds of Renaissance geniuses. Research shows, however, that the key component of the trace italienne, the angled bastion, has its roots in Greek and Roman writing, and in extant constructions by Roman and Byzantine engineers. The angled bastion of the trace italienne was yet another aspect of the resurgent Greek and Roman culture characteristic of the Renaissance along with the traditions of medicine, mathematics, and science. The writings of the ancients were bolstered by physical examples located in important trading and pilgrimage routes. Furthermore, the geometric layout of the trace italienne stems from Ottoman fortifications that preceded it by at least two hundred years. The Renaissance geniuses combined ancient bastion designs with eastern geometry to match a burgeoning threat in the rising power of the siege cannon.

No description available.

An experimental and numerical investigation was conducted to determine the film cooling effectiveness of a normal slot and angled slot under realistic engine Mach number conditions. Freestream Mach numbers of 0.65 and 1.3 were tested. For the normal slot, hot gas ingestion into the slot was observed at low blowing ratios (M < 0.25). At high blowing ratios (M > 0.6) the cooling film was observed to "lift off" from the surface. For the 30o angled slot, the data was found to collapse using the blowing ratio as a scaling parameter (x/Ms). Results from the current experiment were compared with the subsonic data published to confirm this test procedure. For the angled slot, at the supersonic freestream Mach number, the current experiment shows that at the same x/Ms, the film cooling effectiveness increases by as much as 25% as compared to the subsonic case. The results of the experiment also show that at the same x/Ms, the film cooling effectiveness of the angled slot is considerably higher than that of the normal slot, at both subsonic and supersonic Mach numbers. The flow physics for the slot tests considered here are also described with computational fluid dynamic (CFD) simulations in the subsonic and supersonic regimes. / Master of Science

Traveling-wave semiconductor optical amplifiers¡]TWSOAs¡^of symmetric and asymmetric multiple quantum wells¡]MQWs¡^have been implemented by using angled-facet structures. The asymmetric MQWs structures are designed to increase the wavelength range of the gain spectrum. The angled-facet structures, which can suppress gain ripple from FP resonance, are of 3mm-wide and 700mm-long ridge waveguides, and of different angles¡]q¡^at 3o, 5o, 7o, and 9o. From Marcuse¡¦s model, the calculation shows that the angled-facet structures have reflectivities lower than 10-4. We have also developed a single-trench process to fabricate the angled-facet TWSOAs. The l=1.55mm asymmetric structure, which shows a low epitaxial quality of large leakage current, is not suitable for SOA application. For the l=1.3mm asymmetric structure, the threshold current¡]Ith¡^at q=0o was 22.5mA, while at q=7o the Ith increased to 45mA. We have also measured the spectrum below threshold current. The differences between FP resonance peak and valley become smaller at larger q. We estimated that the reflectivity is about 0.2 at 5o. The results show that the reflectivity was decreased by angled-facet structure.

This dissertation provides the first known examples of finite co-volume Kleinian groups which have co- final towers of finite index subgroups with positive rank gradient. We prove that if the fundamental group of an orientable finite volume hyperbolic 3-manifold has fi nite index in the reflection group of a right-angled ideal polyhedron in H^3 then it has a co-fi nal tower of fi nite sheeted covers with positive rank gradient. The manifolds we provide are also known to have co- final towers of covers with zero rank gradient. We also prove that the reflection groups of compact right-angled hyperbolic polyhedra satisfying mild conditions have co-fi nal towers of fi nite sheeted covers with positive rank gradient. / text

There is no evidence in the literature of biomechanical stability characteristics comparing conventional rectangular screw placement with that of an angled mono-cortical screw plating system where standard 2mm diameter screws are applied at angles more acute than conventional 90° screws, through plate holes machined (cut) for a definite specific screw angle placement P. Angled screws will have an obvious clinical advantage of direct line of vision insertion, through an intra-oral route without the disadvantage of trans-buccal (cutaneous) approach required for conventional 90° rectangular screw application. Angled screw application will result in the prevention of possible, less post-operative swelling, nerve fall out (motor and/or sensory), haematoma, false aneurysm and scarring as unwanted clinical complications associated with trans-buccal extra-oral surgical technique. Intra-oral angled screw application will result in definitive cost saving due to less operating time required. Post-treatment removal of angled screws is uncomplicated, requiring only intra-oral surgical approach, without trochar use or skin incisions for screwdriver application. By determining angle displacement values at certain clinical relevant force values for both compression/tension and torsion, preference can be established for ideal angle(s) of screw application in a plating system. An own unique, designed and manufactured, jig and inclined screw insertion (ISI) plates were implemented during the biomechanical evaluation of stability at different screw angle applications in a Zwick machine. For the purpose of this biomechanical comparative investigation an inclined screw insertion (ISI) plate was manufactured with 90°, 75°, 60° and 45° angled plate holes orientated in line with the long-axis (quadrant 3) of the distal section of the plates and diagonal across (quadrant 1) in the proximal section of the plates. Screws with an ISI angle of 30° in any quadrant application resulted in lifting the plate from the bone surface and caused cortical bone destruction during pilot drilling. The results for mono-cortical 7mm screw placement proved superior in biomechanical stability during tension/compression - forces for screw insertion angles of 60° and 45°, when compared to conventional 90° rectangular screw placement. Screws inserted at an angle of 75° demonstrated no improvement in compression/tension stability when compared with 90°.Torsion force stability for all of the 75°, 60° and 45° inclined screw insertion (ISI) systems proved more stable compared to conventional 90° screw angle plates. It is concluded that angled monocortical screw placement between angles 60° and 45° has clinical significance as far as stability, intra-oral surgical technique and time-cost factor is concerned. The results of this biomechanical behaviour investigation of ISI, evolved new terminology such as screw-tip shifting, screw-tip travel, lag potential and clinical significance for the range of screw angle placement. Angled orientation to the plate design and plate geometry is also defined in terms of tension line distribution in the anatomical region for application in the mandible. An unique quadrant description for ISI is described for future communication. An international patent, based on the ISI principle, has been registered for monocortical six-hole plates of firstly different geometric designs to conform to specific anatomical topographic sites in the mandible and secondly specific screw plate-holes angled at 60° in different orientation to the plate (Patent:PCT/EP 2006/006365), (Addendum 6). A specific L-shaped, mandibular angle plate with screw holes at a 60° angle where orientation shifts from in-line with the long-axis of the plate in the distal three plate holes to diagonal orientation in the proximal section of the plate, is designed and manufactured by Stryker/Leibinger as an example of such a patent plate. It is recommended that a smart-lock plate with plate holes at 55° angles be manufactured to allow screw angle placements of 65° - 45° in different angle orientations. Pilot hole drilling and ISI can be performed without the use of a drill-guide. / Thesis (PhD)--University of Pretoria, 2009. / Maxillo-Facial and Oral Surgery / unrestricted

No description available.

This research describes the development and application of a numerical modelling method for angled borehole heat exchangers in ground-source heat pump systems. Inclining the boreholes relative to the vertical axis presents an opportunity to reduce the ground level footprint of the borehole field thus allowing for the installation of geothermal systems in retrofit applications or under buildings with small footprints. The commercial code COMSOL was used to develop the computational model. A series of validation and verification studies were performed to ensure the accuracy of the modelling approach. Simulations were conducted under constant and transient heat injection, where the effect of energy load imbalance is analyzed. Additionally, the effect of discontinuous loading with natural and forced recovery cycles is investigated. When exposed to a constant heat injection rate, configurations of angled borehole heat exchangers initially perform the same as vertical borehole heat exchangers. Then, there is a relatively short period where the angled configurations have slightly decreased performance due to increased thermal interaction in the near surface. At longer times, however, there is a significant benefit in using angled borehole heat exchangers as a result of the increased ground volume in the lower portion of the field. Under transient loading conditions, the conclusions were the same as constant heat injection, although the differences were smaller when the energy loading was balanced. However, when the loading was cooling dominated, by year 10 there was a significantly better performance observed for the angled boreholes. This indicates that the configurations of angled borehole heat exchangers can withstand a higher intensity of imbalanced energy loads compared to vertical configurations. Discontinuous loading was investigated by varying the length of time heat injection would occur on a daily basis. These daily perturbations led to small performance losses in the angled boreholes due to the increased thermal interaction in the near surface. Furthermore, imposing a forced recovery on the system by circulating fluid while heat injection was off did not significantly affect the fluid temperature or ground temperature. / Thesis / Master of Applied Science (MASc)

The objects of study in this thesis are automorphism groups of free and right-angled Artin groups. Right-angled Artin groups are defined by a presentation where the only relations are commutators of the generating elements. When there are no relations the right-angled-Artin group is a free group and if we take all possible relations we have a free abelian group. We show that if no finite index subgroup of a group $G$ contains a normal subgroup that maps onto $mathbb{Z}$, then every homomorphism from $G$ to the outer automorphism group of a free group has finite image. The above criterion is satisfied by SL$_m(mathbb{Z})$ for $m geq 3$ and, more generally, all irreducible lattices in higher-rank, semisimple Lie groups with finite centre. Given a right-angled Artin group $A_Gamma$ we find an integer $n$, which may be easily read off from the presentation of $A_G$, such that if $m geq 3$ then SL$_m(mathbb{Z})$ is a subgroup of the outer automorphism group of $A_Gamma$ if and only if $m leq n$. More generally, we find criteria to prevent a group from having a homomorphism to the outer automorphism group of $A_Gamma$ with infinite image, and apply this to a large number of irreducible lattices as above. We study the subgroup $IA(A_Gamma)$ of $Aut(A_Gamma)$ that acts trivially on the abelianisation of $A_Gamma$. We show that $IA(A_Gamma)$ is residually torsion-free nilpotent and describe its abelianisation. This is complemented by a survey of previous results concerning the lower central series of $A_Gamma$. One of the commonly used generating sets of $Aut(F_n)$ is the set of Whitehead automorphisms. We describe a geometric method for decomposing an element of $Aut(F_n)$ as a product of Whitehead automorphisms via Stallings' folds. We finish with a brief discussion of the action of $Out(F_n)$ on Culler and Vogtmann's Outer Space. In particular we describe translation lengths of elements with regards to the `non-symmetric Lipschitz metric' on Outer Space.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-03T11:32:06Z No. of bitstreams: 1 gustavocanerecruz.pdf: 7258310 bytes, checksum: 5ef1068022f8966d891c48b9cc921f52 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-02T13:20:20Z (GMT) No. of bitstreams: 1 gustavocanerecruz.pdf: 7258310 bytes, checksum: 5ef1068022f8966d891c48b9cc921f52 (MD5) / Made available in DSpace on 2016-07-02T13:20:20Z (GMT). No. of bitstreams: 1 gustavocanerecruz.pdf: 7258310 bytes, checksum: 5ef1068022f8966d891c48b9cc921f52 (MD5) Previous issue date: 2012-12-18 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivos deste estudo retrospectivo foram analisar as taxas de sobrevivência de implantes cuneiformes angulados dentro de longo período de controle e identificar os fatores que podem afetar a sobrevivência destes implantes. Os prontuários de todos pacientes que receberam cuneiformes angulados entre 1992 e 2011 foram revisados de acordo com os seguintes critérios: idade, sexo, tabagismo, doença periodontal prévia, condições sistêmicas; localização, diâmetro, comprimento e angulagem dos implantes; datas de instalação, carregamento, últimos controles, procedimentos adaptativos e tipo de prótese. A sobrevivência foi analisada pelo método de Kaplan-Meier, assim como a identificação dos fatores de risco. Baseado nos resultados da análise univariada, os fatores de risco também foram identificados pelo método da regressão de Cox. Dos implantes revisados, 461 instalados em 120 pacientes (55 homens e 65 mulheres) preencheram os critérios para serem incluídos neste estudo. A média de sobrevivência foi de 148,6±3,9 meses. A sobrevivência global acumulada foi de 95,2% e 92,1% aos 5 e 10 anos, respectivamente. A localização (P =,017), o diâmetro (P =,044) e o ângulo (P =,024) foram identificados como fatores de risco significantes para a perda dos implantes na análise univariada. Na análise multivariada, apenas a localização permaneceu significativa. Implantes cuneiformes angulados são utilizados em locais onde o uso de implantes retilíneos de dimensões padrão não é possível ou não indicado. Portanto, embora as taxas de sobrevivência sejam semelhantes, a sobrevivência dos implantes cuneiformes angulados não deve ser comparada à destes implantes retilíneos. Ela deve ser comparada ao sucesso de procedimentos reconstrutivos ou métodos alternativos como os implantes extra-curtos. Implantes cuneiformes angulados representam um alternativa efetiva para locais onde o uso de implantes retilíleos padrão não está indicado. Devido a características dos resultados e aspectos clínicos, apenas a localização foi considerada um fator de risco significativo para a sobrevivência dos implantes estudados. / The purpose of this study was to analyze retrospectively the survival rate of wedge-shaped angled implants over a long-term follow-up period and to identify factors that affect this survival. The charts and radiographs of all patients who received wedge-shaped angled implants between 1992 and 2011 were examined according to the following criteria: age, gender, tobacco smoking habbit, previous periodontal disease, systemic conditions; location, diameter, length and angulation of the implant, time of placing, loading and last follow-ups; adaptative procedures and type of prosthesis. Survival wan analysed by Kaplan-Meier method, as well as identification of risk factors. Based on the univariate analyses results, risk factors where also identified by Cox regression method. Of the implants reviewed, 461 in 120 patients (55 mens and 65 womans) met the criteria for inclusion in this study. Mean survival was of 148.6±3.9 months. Global cumulative survival rates where 95.2% and 92.1% at 5 and 10 years, respectively. Location (P = .017), diameter (P = .044) and angle (P = .024) were identified as significative risk factor for implant loss at the univariate analysis. At the multivariate analysis, only the location remained significative. Wedge-shaped angled implants are intended to be used in situations that the use of standard dimesions straight implants are not possible. So, although their survival rates are similar, wedge-shaped angled implants survival must be compared to those straight implants, but to the success of reconstrutive procedures or alternative methods like extra-short implants. Wedge-shaped implants represent an effective alternative to sites that are not indicated to standard straight implants placement. Due to results caractheristics and clinical implications, only location was considered as a significant risk factor for implant survival.