44 research outputs found
Additively manufactured (3DP) thermite structures vs conventionally manufactured equivalents
No full textResearch into additive manufacturing (AM) has been steadily expanding over the past five decades. Where once only polymeric materials could be reliably printed, AM has been adapted to print with a range of materials such as biological, metallic, ceramic and even foodstuffs. The advantages of manufacturing in an additive manner include; a) a layer-by-layer approach allows the creation of architecturally complex structures, b) a reduction in weight, c) lessening of waste and d) the ability to create parts that that are otherwise difficult or too costly to produce.
Pyrotechnic materials, including thermites, are used in a wide range of commercial and defence applications. However, hazards present during manufacturing and storage have resulted in major accidents around the world, with subsequent loss of life and in some cases loss of public infrastructure. AM, using a dry powder printing technique means that parts can be manufactured on demand, reducing the need for storage of large volumes of fully formed products or mixes, thus increasing the safety over lifetime of a product.
The performance of pyrotechnics materials is dependent on a number of properties, including chemical composition, thermodynamic properties and physical form. In combination with composition, architecture could be utilised to understand and control these properties. A bespoke printer capable of additively manufacturing pyrotechnic materials has been constructed with the aim to explore this research area.
In this presentation, we compare the burn rates of AM thermites and compare them to conventionally fabricated compositions and discuss the effects of the print parameters and confinement. We conclude with the results from the burning of AM thermite structures and compare their performance with conventionally prepared equivalent thermite examples.45th International Pyrotechnics Society Seminar (2022 IPS Seminar
Design Studios in Civil Engineering Education
No full textWhile the education of civil engineers is presently considered to be at the expected level, the engineering profession consistently points to the lack of integration of technical content in problem solving activities, and the inadequate communication and team-working skills of many graduates. Very often we all come across the students who know the content but can’t seem to apply it and the question that comes to mind is how to re-energise the learning experience for both ourselves and our students? Literature consistently points out that any form of group activity will result in a better quality of student learning when compared to traditional delivery methods (Fink, 2003). Students often point to the obvious inconsequence of much of the course material learned in early years to real engineering problems. Once real design projects are encountered in later years, much of this knowledge has been lost; the application is not obvious or it is considered too theoretical for practical applications. The motivation of students to learn and integrate scientific and technological concepts from early on in their academic career is one of the key objectives for the creation of Civil Engineering Design Studios at a number of universities worldwide, as uncovered by the first author during her recent visit to several Universitas 21 (U21) member institutions as a U21 Fellow. This paper presents some of the findings concerning the Design Studios in Civil Engineering education, as revealed during the Fellowship. Paper presented at ConnectED 2007 International Conference on Design Education, July 200
Thin plate bending analysis and treatment of material discontinuities using the generalised RKP-FSM
No full textA finite strip method (FSM) utilising the generalised reproducing kernel particle method (RKPM) [Behzadan, Shodja, and Khezri (2011)] is developed for the bending analysis of thin plates. In this innovative approach, the spline functions in the conventional spline finite strip method (SFSM) are replaced with generalised RKPM 1-D shape functions in the longitudinal direction, while the transverse cubic functions which are used in the conventional formulations are retained. Since the generalised RKPM is one of the class of meshfree methods which deal efficiently with derivative-type essential boundary conditions, its introduction in the FSM is beneficial for solving boundary value problems such as the bending of thin plates in which a number of essential boundary conditions can include first derivatives of the displacement function. In this paper, the formulation for the generalised RKP-FSM is derived for the analysis of thin plates, and its accuracy and convergence are examined through a series of numerical studies. Moreover, by modifying the concept of the augmented corrected collocation method [Shodja, Khezri, Hashemian, and Behzadan (2010)] a new feature is added to the conventional SFSM and the generalised RKP-FSM which allows for the exact treatment of material discontinuities in bending analysis. Oscillatory behaviour of solutions near the interface of material discontinuities due to Gibb's phenomenon is successfully eliminated in both methods
Thin Plate Bending Analysis and Treatment of Material Discontinuities Using the Generalised RKP-FSM
No full textA finite strip method (FSM) utilising the generalised reproducing kernel particle method (RKPM) [Behzadan, Shodja, and Khezri (2011)] is developed for the bending analysis of thin plates. In this innovative approach, the spline functions in the conventional spline finite strip method (SFSM) are replaced with generalised RKPM 1-D shape functions in the longitudinal direction, while the transverse cubic functions which are used in the conventional formulations are retained. Since the generalised RKPM is one of the class of meshfree methods which deal efficiently with derivative-type essential boundary conditions, its introduction in the FSM is beneficial for solving boundary value problems such as the bending of thin plates in which a number of essential boundary conditions can include first derivatives of the displacement function. In this paper, the formulation for the generalised RKP-FSM is derived for the analysis of thin plates, and its accuracy and convergence are examined through a series of numerical studies. Moreover, by modifying the concept of the augmented corrected collocation method [Shodja, Khezri, Hashemian, and Behzadan (2010)] a new feature is added to the conventional SFSM and the generalised RKP-FSM which allows for the exact treatment of material discontinuities in bending analysis. Oscillatory behaviour of solutions near the interface of material discontinuities due to Gibb's phenomenon is successfully eliminated in both methods
Abstract P6-09-45: Long-term follow-up of early stage breast cancer patients with results of MammaPrint®, Oncotype DX® and MammoStrat® risk classification assays
No full textAbstract
Introduction: The use of genomic tests for the prediction of breast cancer recurrence is becoming more common. MammaPrint® (MP, Agendia Inc.) is a 70-gene microarray assay designed to assess the 10-year risk of recurrence in an untreated population that was not selected for ER/HER2 results. The Oncotype DX® Recurrence Score® (RS, Genomic Health, Inc.) is a 21-gene RT-PCR assay that is clinically validated to predict the 10-year risk of distant recurrence in ER+ patients treated with Tamoxifen. MammoStrat® (MS, Clarient, Inc.) is an IHC assay that uses 5 antibodies and has been validated in a similar population as RS. Several recent reports show that these assays classify patients differently with significant discordances for all risk groups (Shivers, et al., SABCS 2013; Denduluri, et al., ASCO Breast 2011; Poulet, et al., SABCS 2012; Schneider, et al., ASCO 2013). The present study is an analysis of long-term follow-up in a cohort of patients who have results for all three of these risk-stratifying assays side by side in the same samples.
Methods: Patients with ER+ N0-N1 early-stage breast cancer with an MP result obtained as part of their routine clinical care were identified at the University of South Florida (USF, N=65) and Morton Plant Hospital (N=83). After local IRB approval, slides and/or blocks were cut and de-identified at USF and sent to Genomic Health and Clarient for blinded testing. Clinicopathological features were also reviewed by 3 breast pathologists.
Results: 148 patients with an MP result had tissue available to send for RS and MS assays. These patients had a median age of 62 years; median tumor size 1.8 cm; 9% low grade, 59% intermediate grade and 32% high grade. In our previous analysis of this study, of 148 patients with MP results, 53% were low risk and 47% were high risk. Of 135 samples that yielded enough RNA to produce an RS result, 53% were low risk, 26% were intermediate risk and 21% were high risk. Of 129 samples that yielded an MS result, 44% were low risk, 28% were moderate risk and 28% were high risk. Of 121 patients with results for all 3 assays, only 22% were concordant for low risk and 9% were concordant for high risk across all 3 assays. Overall, 30% of cases showed a major discordance such as low risk for one assay and high risk for another. After median follow-up of 54 months, 9 patients have had a distant metastasis and/or 8 patients have died (11 patients total). One patient who had bone metastasis and died had been classified as low risk by all 3 assays. Three patients with distant metastases had a major discordance between assays, with two high risk and one low risk result. Seven patients were classified as high or intermediate/moderate risk by all 3 assays.
Conclusions: This direct comparison demonstrates that although the assays classify a large proportion of patients differently, the patients who ended up with a distant metastasis and/or died of breast cancer had been classified as high risk by at least two of the three assays. This study has important clinical implications since these assays are used to help make treatment decisions regarding which patients might benefit from chemotherapy.
Citation Format: Shivers SC, Russell S, Blumencrancz L, Mehindru A, Acs G, Ellis D, Vrcelj V, Zanchi A, Blumencrancz PW, Carter E, King J, Cox CE. Long-term follow-up of early stage breast cancer patients with results of MammaPrint®, Oncotype DX® and MammoStrat® risk classification assays [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-45.</jats:p
Buckling of the steel component of a composite member caused by shrinkage and creep of the concrete component
No full textThe effects of shrinkage and creep in conventional reinforced and prestressed concrete members are quite well understood, and the effects of these time-varying characteristics of the concrete component on the deflections of composite beams and columns have received a good deal of attention in recent years. However, creep and shrinkage effects may cause a redistribution of internal actions within a composite member, which increases significantly the compression within the steel component, and that may therefore lead to considerations of the possible buckling instability of the steel component. This paper reviews the research work that been documented only quite recently, which has been undertaken on the potential for composite structures using a thin external skin with a concrete infill to buckle locally, and the possible instabilities that may arise in the negative moment region of a continuous composite beam, due to the shrinkage and creep of the concrete. This paper also puts the possibilities of these instabilities into a practical perspective, indicating where this unique type of steel buckling may need to be a design consideration in the most efficient use of steel-concrete composite construction
Putting pressure on elusive polymorphs and solvates
No full textThe reproducible crystallisation of elusive polymorphs and solvates of molecular compounds at high pressure has been demonstrated through studies on maleic acid, malonamide, and paracetamol. These high-pressure methods can be scaled-up to produce bulk quantities of metastable forms that can be recovered to ambient pressure for subsequent seeding experiments. This has been demonstrated for paracetamol form II and paracetamol monohydrate. The studies also show that the particular solid form can be tuned by both pressure and concentration
Dynamic characteristics of reinforced concrete beams
No full textDynamic characteristics of simply supported reinforced concrete (RC) beams of 1200 x 150 x 100 mm were nvestigated by finite element method (FEM), assuming inear behaviour
Detonation properties of additively manufactured RDX: Dry powder printed
No full textResearch into additive manufacturing (AM) has been steadily expanding over the past five decades. Where once only polymeric materials could be reliably printed, AM has been adapted to print with a range of materials such as biological, metallic, ceramic and even foodstuffs. The advantages of manufacturing in an additive manner include; a) a layer-by-layer approach allows the creation of architecturally complex structures, b) a reduction in weight, c) lessening of waste and d) the ability to create parts that that are otherwise difficult or too costly to produce.
1,3,5-Trinitro-1,3,5-triazinane (RDX) is regularly used in explosive systems. Its detonation properties when conventionally manufactured are widely researched and broadly understood. However, recent advances in additive manufacturing technologies have led to greater interest in utilising RDX in this manner. There is growing evidence that emerging formulations and printing methods are changing the detonation properties of RDX composites, the critical diameter among them.1
This study reports on beginning to understand the detonation properties of additively manufactured RDX via a dry powder printing method.First International Explosives Conference (IEC-2022
Cephalexin: a channel hydrate
No full textThe antibiotic cephalexin [systematic name: d-7-(2-amino-2-phenylacetamido)-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid] forms a range of isomorphic solvates, with the maximum hydration state of two water molecules formed only at high relative humidities. The water content of the structure reported here (C16H17N3O4S·1.9H2O) falls just short of this configuration, having three independent cephalexin molecules, one of which is disordered, and 5.72 observed water molecules in the asymmetric unit. The facile nature of the cephalexin solvation/desolvation process is found to be facilitated by a complex channel structure, which allows free movement of solvent in the crystallographic a and b directions
