Establishment of ground vibration prediction model for high-speed trains on embankments

A series of field measurement data is used to establish the prediction model of ground vibration induced by Taiwan high-speed trains on embankments. These measurements consist of various possible influence factors, such as train speed, ground shear wave velocity, and structure volume. The characteristics of near-field ground vibration, far-field vibration propagation, and vibration influence distance are then evaluated from these measurement data. The analyses reveal that the near-field ground vibration level mainly depends on train speed and ground shear wave velocity. The influence of structure volume on the vibration level is minor. The far-field vibration propagation is affected by ground shear wave velocity. The analysis results also show that the attenuation coefficient is different for each frequency range. In general, the measured ground vibration in the high frequency range has the highest attenuation coefficient and that in the low frequency range has the lowest. For the vibration influence distance, the rock can propagate the vibration to the farthest distance among all soil types while the sand/silt/clay soils show the shortest. Finally, a specific ground vibration prediction model is established using these characteristics

2-(1H-Pyrrolo­[2,3-b]pyridin-2-yl)pyridine

In the title compound, C12H9N3, the dihedral angle between the pyridine and aza­indole rings is 6.20 (2)°. In the crystal, pairs of N—H⋯N hydrogen bonds link mol­ecules into inversion dimers

Development of automatic prediction model for ground vibration using support vector machine

This study develops an automatic prediction model for ground vibration induced by Taiwan high-speed trains on embankments. Various field-measured ground vibration data comprise a database used for developing the prediction model. First, the main characteristics that affect the overall vibration level are established on the basis of measurement result database. These main influence factors include train speed, ground condition, measurement distance, and supported structure. A support vector machine (SVM) algorithm, which is a widely used classification model, is then adopted to predict the vibration level induced by high-speed trains on embankments. The measured and predicted vibration levels are compared to verify prediction model reliability. Analytical results show that the more the measured vibration data located in one vibration group is collected, the higher of the accuracy rate will be. Generally, the developed SVM model can reasonably predict ground vibration level in various frequency ranges. Prediction results are discussed in detail, and the methodology for developing the automatic ground vibration level prediction system is presented

Vertical Integration in the Taiwan Aquaculture Industry

The study aims to improve the distribution channels in the Taiwan aquaculture industry through a better vertical integration. This study is derived from a need to improve the distribution performance of agricultural-based industries in response to increasing food demands in Asia and elsewhere. Based on a four-by-eight matrix derived from both a value chain and a service profit chain, thirty different strategies are developed. This development is based on key success factors and strategies for vertical integration interviewed and cited in the literatures. The findings are identified by applying the Gray Relational Analysis (GRA). For this study, the key success factors for aquaculture wholesale markets include the communication, integration and cohesion of opinion within the wholesale market; government support; andmutual trust between members of the vertical integration scheme. The suitable vertical integration strategies are an improved safety and hygiene inspection of aquaculture products, accuracy of aquaculture product categorization, and precision in product weighing.aquaculture industry, grey relational analysis (GRA), channels integration

3,4-Dinitro-2,5-bis­[4-(trifluoro­meth­yl)phen­yl]thio­phene

The title compound, C18H8F6N2O4S, is a precursor for the production of low-band-gap conjugated polymers. In the crystal structure, the dihedral angles between the thio­phene and benzene rings are 35.90 (8) and 61.94 (8)°, and that between the two benzene rings is 40.18 (8)°. The two nitro groups are twisted with respect to the thio­phene ring, the dihedral angles being 53.66 (10) and 31.63 (10)°. Weak inter­molecular C—H⋯O hydrogen bonding helps to stabilize the crystal structure

Preparation of Monodisperse Iron Oxide Nanoparticles via the Synthesis and Decomposition of Iron Fatty Acid Complexes

Iron fatty acid complexes (IFACs) are prepared via the dissolution of porous hematite powder in hot unsaturated fatty acid. The IFACs are then decomposed in five different organic solvents under reflux conditions in the presence of the respective fatty acid. The XRD analysis results indicate that the resulting NPs comprise a mixture of wustite, magnetite, and maghemite phases. The solvents with a higher boiling point prompt the formation of larger NPs containing wustite as the major component, while those with a lower boiling point produce smaller NPs with maghemite as the major component. In addition, it is shown that unstable NPs with a mixed wustite–magnetite composition can be oxidized to pure maghemite by extending the reaction time or using an oxidizing agent

Non-prompt surgery for patients with acute type A aortic dissection without pre-operative shock and malperfusion

BackgroundAcute type A aortic dissection (ATAAD) requires urgent surgical treatment. However, during daily practice, there were some patients with ATAAD sought for medical attention several days after symptoms occurred and some other patients hesitated to receive aortic surgery after the diagnosis of ATAAD was made. This study aims to investigate the surgical outcomes of non-prompt aortic surgery (delayed diagnosis caused by the patient or delayed surgery despite immediate diagnosis) for ATAAD patients.MethodsFrom November 2004 to June 2020, of more than 200 patients with ATAAD patients who underwent aortic surgery at our hospital, there were 30 patients without pre-operative shock and malperfusion who sought for medical attention with symptoms for several days or delayed aortic surgery several days later despite ATAAD was diagnosed. Of the 30 patients (median age 60.9, range 33.4~82.5 years) in the study group, there were 18 patients undergoing surgery when they arrived at our hospital (delayed diagnosis by the patient) and 12 patients receiving surgery days later (delayed surgery despite immediate diagnosis). Patients with prompt surgery after symptom onset (control group) were matched from our database by propensity score matching. The surgical mortality rate and post-operative morbidities were compared between the study group and control group.ResultsThe in-hospital mortality was 3.3% for the study group and 6.7% for the control group (p = non-significant). The incidence of post-operative cerebral permanent neurological defect was 0% for the study group and 13.3% for the control group (p = 0.112). There were three patients receiving aortic re-intervention or re-do aortic surgery during follow-up for the study group and two patients for the control group.ConclusionPrompt surgery for ATAAD is usually a good choice if everything is well prepared. Besides, urgent but non-prompt aortic surgery could also provide acceptable surgical results for ATAAD patients without pre-operative shock and malperfusion who did not seek medical attention or who could not make their minds to undergo surgery immediately after symptom onset. Hospitalization with intensive care is very important for pre-operative preparation and monitoring for the patients who decline prompt aortic surgery

Observation of Temperature-Induced Crossover to an Orbital-Selective Mott Phase in Ax_{x}Fe2−y_{2-y}Se2_2 (A=K, Rb) Superconductors

In this work, we study the A$_{x}$Fe$_{2-y}$Se$_2$ (A=K, Rb) superconductors using angle-resolved photoemission spectroscopy. In the low temperature state, we observe an orbital-dependent renormalization for the bands near the Fermi level in which the dxy bands are heavily renormliazed compared to the dxz/dyz bands. Upon increasing temperature to above 150K, the system evolves into a state in which the dxy bands have diminished spectral weight while the dxz/dyz bands remain metallic. Combined with theoretical calculations, our observations can be consistently understood as a temperature induced crossover from a metallic state at low temperature to an orbital-selective Mott phase (OSMP) at high temperatures. Furthermore, the fact that the superconducting state of A$_{x}$Fe$_{2-y}$Se$_2$ is near the boundary of such an OSMP constraints the system to have sufficiently strong on-site Coulomb interactions and Hund's coupling, and hence highlight the non-trivial role of electron correlation in this family of iron superconductors

Synthesis and characterization of new fluorescent two-photon absorption chromophores{

A series of dipolar and quadrupolar type two-photon absorption (TPA) compounds has been synthesized and TPA cross sections (s) were measured by Ti:sapphire femtosecond laser excitation fluorescence (l = 800 nm). Among them, the compound ) can be achieved. One quadrupolar molecule (13) possessing an arylamine donor and a pyridazine acceptor has both a high s value (1442 GM) and s/MW (1.97 GM/g)

Patients Infected with CRF07_BC Have Significantly Lower Viral Loads than Patients with HIV-1 Subtype B: Mechanism and Impact on Disease Progression

The circulating recombinant form (CRF) 07_BC is the most prevalent HIV-1 strain among injection drug users (IDUs) in Taiwan. It contains a 7 amino-acid deletion in its p6gag. We conducted a cohort study to compare viral loads and CD4 cell count changes between patients infected with subtype B and CRF07_BC and to elucidate its mechanism. Twenty-one patients infected with CRF07_BC and 59 patients with subtype B were selected from a cohort of 667 HIV-1/AIDS patients whom have been followed up for 3 years. Generalized estimated equation was used to analyze their clinical data and the results showed that patients infected with CRF07_BC had significantly lower viral loads (about 58,000 copies per ml less) than patients with subtype B infection (p = 0.002). The replicative capacity of nine CRF07_BC and four subtype B isolates were compared and the results showed that the former had significantly lower replicative capacity than the latter although all of them were CCR5- tropic and non-syncytium inducing viruses. An HIV-1-NL4-3 mutant virus which contains a 7 amino-acid deletion in p6gag (designated as 7d virus) was generated and its live cycle was investigated. The results showed that 7d virus had significantly lower replication capacity, poorer protease-mediated processing and viral proteins production. Electron microscopic examination of cells infected with wild-type or 7d virus demonstrated that the 7d virus had poorer and slower viral maturation processes: more viruses attached to the cell membrane and higher proportion of immature virions outside the cells. The interaction between p6gag and Alix protein was less efficient in cells infected with 7d virus. In conclusion, patients infected with CRF07_BC had significantly lower viral loads than patients infected with subtype B and it may due to the deletion of 7 amino acids which overlaps with Alix protein-binding domain of the p6gag