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Aerodynamic optimisation of Formula student vehicle using computational fluid dynamics
Get PDFThis work aims to improve the external aerodynamic characteristics of the 2017 University of Huddersfield Formula SAE vehicle. To improve dynamic performance in the SAE events, a multiple-element rear wing was developed, which incorporated adjustable elements to constitute a drag reduction system (DRS). A numerical modelling approach was adopted to produce a suitable design. A simplified model of the vehicle was created to obtain baseline coefficients of lift (CL) and drag (CD). The rear wing was optimised to find the peak configuration generating maximum downforce. The results show that the incorporated rear wing improved the vehicle’s CL from 0.21 acting in the positive Y axis (lift) to 1.15 acting in the negative Y axis (downforce), whereas the CD increased from 0.71 to 1.21. However, the DRS configuration reduced the CD to 0.79. Using the obtained lift and drag coefficients, vehicle performance was estimated, such as maximum cornering speed, straight-line top speed and straight-line acceleration capabilities. The rear wing improved the theoretical maximum cornering speed by 3.1% for a corner radius of 13 m. The DRS increased the theoretical top speed by 18.2% compared to a fixed wing configuration. Acceleration potential increased by 15.7% at 25 m/s with the DRS open. The final section of the study used an online simulator (FSAESim) to make predictions of the acceleration event time, which were compared to the track results from the 2017 Hungary SAE event. The results showed a 97% similarity
The Value and Meaning of Temporality and its Relationship to Identity in Kunming City, China
No full textThis study aims to highlight the changing relationships between the city and its modes of representation, through an examination of the historical transformations of Kunming, a city on the southwest borderland of China. Our intention here is to introduce to the reader particular characteristics of urban space in Kunming as the basis for a more detailed examination of the historical differences between Western and Chinese perspectives of temporality in building, to be explored in a forthcoming book, and how these differences are manifested in the changing social contexts of the city.
The study demonstrates that changes in the territorialised districts of the traditional city of Kunming after the Qing dynasty, constitute a movement towards modernization. This development moreover gave rise to a distinctive type of mercantile space within the city centre, with the increasing importance attached to the commercial street. Importantly this feature of the urban topography of Kunming can be seen to relate closely to the surrounding mountains and lakes both within and outside the old city boundaries that have served as primary reference points in urban planning. The study seeks to establish if the traditional meanings of temporality in building, as they are manifested within the particular urban grain of Kunming, still inform contemporary urban and architectural practice given that such relationships are often concealed beneath the homogeneous image of the temporary city
Book Review: NEIL RAMSEY, The Military Memoir and Romantic Literary Culture, 1780-1835 (Farnham: Ashgate, 2011)
No full textCrime Concentrations: Hot Dots, Hot Spots and Hot Flushes
No full textEvery research enterprise takes place in a context, political, economic, and technological. So it is with policing research. We begin by sketching out where we think the practice of policing is heading, and what we need to do differently, so as to get to a roughly envisioned future ethically and in good order. A police presence at all places at all times being impossible, the practical issue is where and when to place officers or their technological surrogates. The chapter will consider optimised distribution of effort and resource, given the central aim of fairness in the distribution of crime harm. We will illustrate current levels of inequality of victimisation, and claim that reducing the current concentration, at individual and area levels, should be an explicit underpinning vision for policing. We briefly review the relevant literature and its implications
Model-based Chatter Stability Prediction and Detection for the Turning of a Flexible Workpiece
No full textMachining long slender workpieces still presents a technical challenge on the shop floor due to their low stiffness and damping. Regenerative chatter is a major hindrance in machining processes, reducing the geometric accuracies and dynamic stability of the cutting system. This study has been motivated by the fact that chatter occurrence is generally in relation to the cutting position in straight turning of slender workpieces, which has seldom been investigated comprehensively in literature. In the present paper, a predictive chatter model of turning a tailstock supported slender workpiece considering the cutting position change during machining is explored. Based on linear stability analysis and stiffness distribution at different cutting positions along the workpiece, the effect of the cutting tool movement along the length of the workpiece on chatter stability is studied. As a result, an entire stability chart for a single cutting pass is constructed. Through this stability chart the critical cutting condition and the chatter onset location along the workpiece in a turning operation can be estimated. The difference between the predicted tool locations and the experimental results was within 9% at high speed cutting. Also, on the basis of the predictive model the dynamic behavior during chatter that when chatter arises at some cutting location it will continue for a period of time until another specified location is arrived at, can be inferred. The experimental observation is in good agreement with the theoretical inference. In chatter detection respect, besides the delay strategy and overlap processing technique, a relative threshold algorithm is proposed to detect chatter by comparing the spectrum and variance of the acquired acceleration signals with the reference saved during stable cutting. The chatter monitoring method has shown reliability for various machining conditions
What do physiotherapist and manual handling advisors consider the safest lifting posture, and do back beliefs influence their choice?
Get PDFBackground: It is commonly believed lifting is dangerous and the back should be straight during lifting. These beliefs may arise from healthcare professionals, yet no study has evaluated the lifting and back beliefs of manual handling advisors (MHAs) and physiotherapists (PTs).
Objectives: To evaluate (i) what lifting technique MHAs and PTs perceive as safest, and why, and (ii) the back pain beliefs of MHAs with PTs.
Design: Data was collected via an electronic survey.
Method: Participants selected the safest lifting posture from four options: two with a straight back and two with a more rounded back, with justification. Back beliefs were collected via the Back-Pain Attitudes Questionnaire (Back-PAQ). Relationships were investigated using multiple linear and logistic regression models.
Results: 400 PTs and MHAs completed the survey. 75% of PT and 91% of MHAs chose a straight lifting posture as safest, mostly on the basis that it avoided rounding of the back. MHAs scored significantly higher than PTs on the Back-PAQ instrument (mean difference = 33.9), indicating more negative back beliefs. Those who chose the straight back position had significantly more negative back beliefs (mean 81.9, SD 22.7) than those who chose a round back lift (mean 61.7, SD 21.1).
Conclusion: Avoiding rounding the back while lifting is a common belief in PT and MHA, despite the lack of evidence that any specific spinal posture is a risk factor for low back pain. MHAs, and those who perceived a straight back position as safest, had significantly more negative back beliefs
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