Three essays on financial intermediation

Financial intermediation plays a central role in connecting capital demanders, i. e. firms, and capital suppliers, i. e. investors. My essays focus on two types of financial intermediaries, namely investment banks, who provide a variety of services for firms and institutional investors, and sell-side security analysts, who analyze and provide information about firms, mainly, to institutional investors. The first essay studies security analysts’ cognitive biases in issuing earnings forecasts; the second essay studies analysts’ capital expenditure forecasts; and, the third essay studies the underwriting relationship value between investment banks and their client firms

Geometric nonlinear vibration analysis of steel frames with semi-rigid connections and rigid-zones

To obtain an accurate insight into the behavior of the most realistic steel frames, joint flexibility should be allowed for in the analysis. So far, most research work is concentrated on the linear and geometric nonlinear static analysis of steel frames with flexible connections. Very few papers were contributed to the dynamic and vibration analysis of these types of frames. This paper proposes a numerical method for geometric nonlinear vibration analysis of frames with semi-rigid connections and rigid-zones. The effect of initial stress due to the applied load is accounted for in the suggested method, which is believed to be more general than the existing methods and does not involve complex calculations

Dynamic stiffness method for free vibrations analysis of partial fluid-filled orthotropic circular cylindrical shells

Free vibrations of partial fluid-filled orthotropic circular cylindrical shells are investigated using the Dynamic Stiffness Method (DSM) or Continuous Element Method (CEM) based on theFirst Order Shear Deformation Theory (FSDT) and non-viscous incompressible fluid equations. Numerical examples are given for analyzing natural frequencies and harmonic responses of cylindrical shells partially and completely filled with fluid under various boundary conditions. The vibration frequencies for different filling ratios of cylindrical shells are obtained and compared with existing experimental and theoretical results which indicate that the fluid filling can reduce significantly the natural frequencies of studiedcylindrical shells. Detailed parametric analysis is carried out to show the effects of some geometrical and material parameters on the natural frequencies of orthotropic cylindrical shells. The advantages of this current solution consist in fast convergence, low computational cost and high precision validating for all frequency ranges

An Assessment of the Values of French Colonial Townhouses in Hanoi Towards A More Sustainable Conservation

As the capital city of French Indochina, Hanoi was well planned by the French and immensely invested in the construction of public buildings as well as houses. In addition to public buildings and villas designed in French colonial styles that shaped the so-called distinctive architectural heritage in Hanoi throughout the colonial years, a large number of townhouses built during 1920 - 1950 which formed the cityscape of Hanoi in the first half of the 20th century should be noted. After nearly 70 years since the French army withdrew from the city, the number of French townhouses has considerably decreased. The remaining houses have shown that this is a real “treasure” that needs to be conserved because of their important values, not only in terms of urban architecture but also in cultural and historical aspects. However, a fact requiring special attention is that French townhouses in Hanoi - unlike French public buildings and villas - have not yet been recognised as heritage so that they can be kept to avoid the risk of deterioration or demolition under the impact of rapid urbanisation in the market economy. One of the main reasons for this negative urban development is that there has been no concrete or comprehensive rating system to assess the values of those townhouses which will closely correspond to their characteristics and contexts. Therefore, the authors - based on site surveys and by applying some appropriate methods such as expert consultations and case studies - have developed a full set of criteria to help evaluate those remaining townhouses as accurately as possible. This system can be used as a basis for a systematic assessment and classification towards a more effective conservation and even promoting the values of those townhouses with regard to the development of a modern society and in consideration of sustainable heritage conservation as a mainstream in the world.

Preparation of some new benzo[d]thiazole derivatives

In this work, four new benzo[d]thiazole derivatives were synthesized successfully from vanillin. Nitration of vanillin gave nitrovanillin followed by cyclization reaction with o-aminothiophenol under microwave irradiation in 4 minutes to give nitroaromatic compound 3. The reduction to convert the nitro group to amino group was optimized. It was found that Fe/ con. HCl in ethanol was the best condition for this case about both yield (~95 %) and simple procedure to give compound 4 as a salt. Acetylation occurs at both phenolic hydroxyl group and amino group of the salt 4 to form N,O-acetyl compound 5. Under mild hydrolysis 5 produces N-acetyl compound 6. The structures of these compounds were established by IR, 1H and 13C NMR and mass spectral analyses. Keywords. benzo[d]thiazole, vanillin, reduction, microwave

User Selection Approaches to Mitigate the Straggler Effect for Federated Learning on Cell-Free Massive MIMO Networks

This work proposes UE selection approaches to mitigate the straggler effect for federated learning (FL) on cell-free massive multiple-input multiple-output networks. To show how these approaches work, we consider a general FL framework with UE sampling, and aim to minimize the FL training time in this framework. Here, training updates are (S1) broadcast to all the selected UEs from a central server, (S2) computed at the UEs sampled from the selected UE set, and (S3) sent back to the central server. The first approach mitigates the straggler effect in both Steps (S1) and (S3), while the second approach only Step (S3). Two optimization problems are then formulated to jointly optimize UE selection, transmit power and data rate. These mixed-integer mixed-timescale stochastic nonconvex problems capture the complex interactions among the training time, the straggler effect, and UE selection. By employing the online successive convex approximation approach, we develop a novel algorithm to solve the formulated problems with proven convergence to the neighbourhood of their stationary points. Numerical results confirm that our UE selection designs significantly reduce the training time over baseline approaches, especially in the networks that experience serious straggler effects due to the moderately low density of access points.Comment: submitted for peer review

Pencil lead graphite electrochemically modified with polyglutamic acid as a sensor for detection of enrofloxacin in aqueous media

This study investigates the modification of pencil lead graphite electrodes with polyglutamic acid using an effective and fast static method to develop a sensor for the detection of enrofloxacin (ENR). The successful fabrication of pGA on the electrode surface was confirmed by scanning electron microscopy, energy dispersive X-ray analysis, and Fourier-transform infrared spectroscopy. The conditions of electrochemical modification, including the applied potentials and number of cycles in the potentiostatic process, were systematically investigated to determine their effects on the ENR electrochemical response. The pH of the electrolyte media was also explored to elucidate the electrochemical reaction mechanism of ENR. The developed electrochemical sensor was evaluated using square wave stripping voltammetry for ENR detection. Under optimal conditions, the sensor demonstrated good reproducibility with a relative standard deviation of 4.3% (from five measurements) for ENR signal detection. A linear relationship between ENR concentration and its peak current was observed in the concentration range of 0.1 to 5 µM, with a high correlation coefficient of 0.9988. The limit of detection for ENR using the sensor was 0.12 µM. Our findings provide valuable insights into the design and optimisation of pencil lead graphite electrode-based sensors for ENR detection in aqueous media