Follow-up radiographs are usually used as the reference standard for the diagnosis of suspected scaphoid fractures. However, these are prone to errors in interpretation. We performed a meta-analysis of 30 clinical studies on the diagnosis of suspected scaphoid fractures, in which agreement data between any of follow-up radiographs, bone scintigraphy, magnetic resonance (MR) imaging, or CT could be obtained, and combined this with latent class analysis to infer the accuracy of these tests on the diagnosis of suspected scaphoid fractures in the absence of an established standard. The estimated sensitivity and specificity were respectively 91.1% and 99.8% for follow-up radiographs, 97.8% and 93.5% for bone scintigraphy, 97.7% and 99.8% for MRI, and 85.2% and 99.5% for CT. The results were generally robust in multiple sensitivity analyses. There was large between-study heterogeneity for the sensitivity of follow-up radiographs and CT, and imprecision about their sensitivity estimates. If we acknowledge the lack of a reference standard for diagnosing suspected scaphoid fractures, MRI is the most accurate test; follow-up radiographs and CT may be less sensitive, and bone scintigraphy less specific.

The effect of biodiesel addition to diesel on engine performance, combustion, and emissions were studied in a turbocharged, high-pressure common rail diesel engine. Biodiesel/diesel blends with different biodiesel fractions were used and compared with neat biodiesel and diesel at different engine loads and speeds. The results show that the brake thermal efficiency increases slightly as biodiesel is added to diesel. Exhaust gas temperature is not significantly affected at low engine speeds and decreases gradually at high engine speeds with an increase in biodiesel fraction. Fuel injection includes both pilot and main injections. Diesel and biodiesel give a similar start to the heat release. The first peak in the heat release rate for biodiesel is lower than that of diesel, while the second peak is higher for biodiesel. The heat release rate curve for biodiesel indicates that the use of biodiesel increases thermal efficiency and NO x emission compared to that of diesel especially at high engine loads. Hydrocarbon and CO emissions maintain very low values and little variation is seen for the different fuels. CO2 emission decreases with increasing biodiesel fraction in the blends. The level of NO x emission decreases slightly at low engine loads and increases at high engine loads with increasing biodiesel fraction. Biodiesel reduces particulate matter (PM) emission significantly and PM reduction effectiveness is increased at high engine loads and/or speed. The oxygen in biodiesel plays a key role in reducing PM emission. Biodiesel/diesel blends can improve performance and decrease emissions for turbocharged, high-pressure common rail diesel engines.

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The variation rules of strength, load, and reliability of mechanical components are studied with a change in time, and a model is established for dynamic reliability of mechanical components under the random load acting. According to the model, the design of dynamic reliability sensitivity is discussed, and the approach to calculate it is proposed. By combining the theory of reliability-based optimization design with the method of sensitivity analysis, the computational method of dynamic reliability-based robust optimization design is established, and the problem of dynamic reliability-based robust optimization design of a torsion bar is solved.