Composite load spectra for select space propulsion structural components

This report summarizes the development for: (1) correlation fields; (2) applications to liquid oxygen post; (3) models for pressure fluctuatios and vibration loads fluctuations; (4) additions to expert systems; and (5) scaling criteria. Implementation to computer code is also described. Demonstration sample cases are included with additional applications to engine duct and pipe bend

Staging achilles tendinopathy using ultrasound imaging: The development and investigation of a new ultrasound imaging criteria based on the continuum model of tendon pathology

AimTo develop a standardised ultrasound imaging (USI)-based criteria for the diagnosis of tendinopathy that aligns with the continuum model of tendon pathology. Secondary aims were to assess both the intra-rater and inter-rater reliability of the criteria.MethodsA criteria was developed following a face validity assessment and a total of 31 Achilles tendon ultrasound images were analysed. Intra-rater and inter-rater reliability were assessed for overall tendinopathy stage (normal, reactive/early dysrepair or late dysrepair/degenerative) as well as for individual parameters (thickness, echogenicity and vascularity). Quadratic weighted kappa (kw) was used to report on reliability.ResultsIntra-rater reliability was ‘substantial’ for overall tendinopathy staging (kw rater A; 0.77, 95% CI 0.59 to 0.94, rater B; 0.70, 95% CI 0.52 to 0.89) and ranged from ‘substantial’ to ‘almost perfect’ for thickness (kw rater A; 0.75, 95% CI 0.59 to 0.90, rater B; 0.84, 95% CI 0.71 to 0.98), echogenicity (kw rater A; 0.78, 95% CI 0.62 to 0.95, rater B; 0.73, 95% CI 0.58 to 0.89) and vascularity (kw rater A; 0.86, 95% CI 0.74 to 0.98, rater B; 0.89, 95% CI 0.79 to 0.99). Inter-rater reliability ranged from ‘substantial’ to ‘almost perfect’ for overall tendinopathy staging (kw round 1; 0.75, 95% CI 0.58 to 0.91, round 2; 0.81, 95% CI 0.63 to 0.99), thickness (kw round 1; 0.65, 95% CI 0.48 to 0.83, round 2; 0.77, 95% CI 0.60 to 0.93), echogenicity (kw round 1; 0.70, 95% CI 0.54 to 0.85, round 2; 0.76, 95% CI 0.58 to 0.94) and vascularity (kw round 1; 0.89, 95% CI 0.79 to 0.99, round 2; 0.86, 95% CI 0.74 to 0.98). Inter-rater reliability increased from ‘substantial’ in round 1 (kw 0.75, 95% CI 0.58 to 0.91) to ‘almost perfect’ in round 2 (0.81, 95% CI 0.63 to 0.99).ConclusionIntra-rater and inter-rater reliability were ‘substantial’ to ‘almost perfect’ when utilising an USI-based criteria to diagnose Achilles tendinopathy. This is the first study to use the continuum model of tendon pathology to develop an USI-based criteria to diagnose tendinopathy

Composite Load Spectra for Select Space Propulsion Structural Components

Generic load models are described with multiple levels of progressive sophistication to simulate the composite (combined) load spectra (CLS) that are induced in space propulsion system components, representative of Space Shuttle Main Engines (SSME), such as transfer ducts, turbine blades and liquid oxygen (LOX) posts. These generic (coupled) models combine the deterministic models for composite load dynamic, acoustic, high-pressure and high rotational speed, etc., load simulation using statistically varying coefficients. These coefficients are then determined using advanced probabilistic simulation methods with and without strategically selected experimental data. The entire simulation process is included in a CLS computer code. Applications of the computer code to various components in conjunction with the PSAM (Probabilistic Structural Analysis Method) to perform probabilistic load evaluation and life prediction evaluations are also described to illustrate the effectiveness of the coupled model approach

Developing Earthquake-Resistant Structural Design Standard for Malaysia Based on Eurocode 8: Challenges and Recommendations

In late 2017, the Malaysian National Annex (NA) to Eurocode 8 (EC8) was released and enacted following some 13 years of deliberations and preparations. The authors of this paper aim to use this article to share their experiences and reflections during this period of developing the first national standard for the seismic design of buildings for Malaysia. To begin with, there were major challenges in implementing the 20-year-old EC8 framework for a country so far away from Europe. The first challenge was adapting the probabilistic seismic hazard assessment (PSHA) methodology in a low-to-moderate seismicity region where the paucity of representative seismic data presented a great deal of uncertainties. To address this situation, imposing a minimum level of seismic hazard was recommended. The second challenge was about dealing with the outdated EC8 site classification scheme, which poorly represents the potential effects of soil amplification in certain geological settings. To address this situation, an alternative site classification scheme in which the site natural period is an explicit modelling parameter was introduced. The third challenge was concerned with difficulties generated by the EC8 provisions mandating Ductility Class Medium (DCM) detailing in certain localities where the level of seismic hazard is predicted to exceed a certain threshold. To address this situation, the viable option of using strength to trade off for ductility was recommended, or in cases where ductility design is needed, a simplified set of code-compliant DCM designs was presented. The fourth challenge was about handling the requirements of EC8 that the majority of buildings are to involve dynamic analysis in their structural design when the majority of practising professionals did not have the skills of exercising proper use of the requisite software. To address this situation, a generalized force method was introduced to control the use dynamic analysis in commercial software. It is hoped that, through sharing the lessons learnt, code drafters for the future would be able to find ways of circumventing the multitude of challenges with clear thinking and pragmatism

Construction of a Teaching Package on Promoting Prosocial Internet Use and Preventing Antisocial Internet Use

In the construction of the teaching package on the Internet use, two major moral characters, respect and responsibility, form the core theoretical basis. The respect character consists of respect for others and self-respect while the responsibility character contains social, civil, and global responsibility. There are a total of nine units on the Internet use in the junior secondary curriculum. There are two units in Secondary One curriculum: the first unit deals with cheating behavior and privacy issues concerning the Internet, and the second one discusses the effect of excessive use of the Internet on life and study. In Secondary Two curriculum, we discuss the following social phenomena on the Internet with students: online shopping, pornographic materials on internet, and infringement of a copyright. Finally, we have designed four units on the Internet use in Secondary Three curriculum which focuses more on the relationship between the Internet use and our health. We try to answer the question on how we can use the Internet healthily and also the possibility on how it may hurt us. Similar to the second unit in Secondary One curriculum, we have designed three more units on discussing the effects of excessive use of the Internet with students. We would like to alert students that ineffective use of the Internet will hurt us mentally and physically. For illustrative purposes, two units in the Secondary One and Two curriculums are outlined in this paper

A preliminary design tool for volumetric buildings

Volumetric building (VB) is a type of off-site construction to move towards high productivity construction. Literature review shows that there are only few models for upstream feasibility study for VB, while many researchers delved into advanced structural engineering aspects of VB modeling (i.e., downstream detailed and technical design). However, there is a lack of guidance for the preliminary design of VB, which is an essential stage that falls in between upstream feasibility study and downstream detailed and technical design. Hence, this paper is written to fill that gap by proposing a new design tool for VB, anchored upon the “desire path” philosophy, which is often used in urban planning, that is, natural formations evident from preceding experiences. Literature review also shows that a comprehensive VB database is not available. Hence, a new database is collected with 31,185 units of modules and 911 module types, sourced from VB projects worldwide to provide a broad global overview. The proposed tool has a systematic framework of a four-quadrant plot for preliminary VB design, enabling designers to determine the number of modules, size of modules, massing typology, and module construction material through new empirical relationships.</p