Persistent Asset Mispricing: Variations on a Simultaneous Move Game

The purpose of this paper will be to demonstrate instances of persistent asset mispricing. By persistent we mean the existence and achievement of a stable equilibrium where market prices deviate from an underlying fundamental value. These equilibria will be demonstrated through three variations on a general model in which agents make investment decisions on an initial public offering (IPO), given imperfect information on a stock’s true, fundamental value. The first variation holds agents’ beliefs fixed, and trades are conducted “blindly” through a market maker who clears the market by adjusting the stock price. The model establishes a case for initial mispricing in the market, resulting from a sub-optimal quantity of outstanding shares. The second variation allows for agents to update beliefs on price movements, and ultimately identifies an unstable equilibrium where the asset is correctly priced. The third and final variation removes the “blind” game conditions, and allows for agents to update beliefs on public signals generated by other agents’ investment decisions. This latter most model successfully demonstrates persistent asset mispricing, given an initial mispricing in the market

Experimental assessment of mechanical behavior of a compressed stabilized earth blocks (CSEB) and walls

The use of compacted stabilized earth blocks (CSEB) in load-bearing masonry is largely developed during these last decades. This paper reports on an experimental study of the chemical and mechanical stabilization effects on the compressive strength of earth blocks and triplet/walls. The blocks prepared with a high sandy soil mixed with rising cement and/or lime contents and compacted at 7 MPa are tested in uniaxial compression. The triplet and walls built with these CSEB units were joined with a cement/earth mortar.Static uniaxial compression tests are typically undertaken on samples of earth mortars, on single earth blocks, on triplets of blocks with and without mortar, and lastly on masonry specimens made of CSEB. Compression tests were performed on CSEB blocks and mortar by using a video extensometer for accurate contactless strain measurement. Mechanical parameters were thus determined, including compressive strength, Poisson’s ratio, and elastic modulus. The results show that the compressive strength values of earth blocks treated with stabilizers were generally increased by rising the additive content. The increase of earth/cement blocks resistances was found more marked in comparison with those of earth/lime. It was also observed that the blocks prepared with an optimal content of lime along with cement have led to continuous increases of mechanical strength up to values greater than 5 MPa. The relationship between the blocks and triplets' compressive strengths as a function of stabilizer content (cement/lime) is linear. In the range of cement content from 6 to 8 %, the compressive strength of triplets is respectively 16 % and 20 % higher than those of walls. The observed failure of triplets and walls occurred essentially by the propagation of vertical and diagonal crack

Earth Construction Durability: In-Service Deterioration of Compressed and Stabilized Earth Block (CSEB) Housing in Algeria

The present work deals with a unique in-service valuation of CSEB structures in Algeria. The inspection tries to bring out the impact of long time exposure under different and opposite climate and micro-seismic contexts. The diagnosis methodology is inspired by the approach largely adopted for the rehabilitation of traditional architecture. It involves the compilation of the previous survey reports, visual inspection of the structures, in-situ and laboratory tests to assess the residual CSEB mechanical properties. The CSEB constructions are located in the coastal north and the desertical south part of Algeria and were exposed respectively to a long-term Mediterranean and Saharian climate. The results of the investigation show that the CSEB in the construction located in the northern region is increasingly altered by the humidity. As the relative humidity rises, the fouling layers grow over some level. The surface pitting which is the consequence of long exposure to the wetting/drying cycles is also observed. The outer surfaces of the walls were honeycombed which reduce drastically the block resistance against the abrasion test. In some cases, differential erosion appears in the front of the walls, which indicates that the alteration does not proceed at the same rate from one area of the block to the other. However, owing to highly cementitious mortar used to join the earth blocks, the edges and corners remain unchipped. In the southern region where the arid climate dominating, the degradation of the CSEB is less prone to water attack but roughly exposed to the effect of the winddust frequent in this region and to the unawareness of the population. The paper presents also some recommendations to improve the earth construction durability with CSEB technique

3D meso-scale modelling of concrete material in spall tests

Tensile strength is one of the key factors of concrete material that need be accurately defined in analysis of concrete structures subjected to high-speed impact loads. Dynamic tensile strength of concrete material is usually obtained by conducting laboratory tests such as direct tensile test, Brazilian splitting test and spall test. Concrete is a heterogeneous material with different components, but is conventionally assumed to be homogeneous, i.e., cement mortar only, in most previous experimental or numerical studies. The aggregates in concrete material are usually neglected owing to testing limitation and numerical simplification. It has been well acknowledged that neglecting coarse aggregates might not necessarily give accurate concrete dynamic material properties. In the present study, a 3D meso-scale model of concrete specimen with consideration of cement mortar and aggregates is developed to simulate spall tests and investigate the behaviour of concrete material under high strain rate. The commercial software LS-DYNA is used to perform the numerical simulations of spall tests. The mesh size sensitivity is examined by conducting mesh convergence tests. The reliability of the numerical model in simulating the spall tests is verified by comparing the numerical results with the experimental data from the literature. The influence of coarse aggregates on the experimental test results is studied. The wave attenuation in concrete specimen is analysed, and empirical equations are proposed for quick assessment of the test data to determine the true dynamic tensile strength of concrete material. The contributions of aggregates to dynamic strength in spall tests are quantified for modifying the test results based on mortar material in the literature

Spalling uniaxial strength of Al2O3 at high strain rates

In this article research into the uniaxial tensile strength of Al2O3 monolithic ceramic is presented. The experimental procedure of the spalling of long bars is investigated from different approaches. This method is used to obtain the tensile strength at high strain rates under uniaxial conditions. Different methodologies proposed by several authors are used to obtain the tensile strength. The hypotheses needed for the experimental set-up are also checked, and the requirements of the set-up and the variables are also studied by means of numerical simulations. The research shows that the shape of the projectile is crucial to achieve successfully tests results. An experimental campaign has been carried out including high speed video and a digital image correlation system to obtain the tensile strength of alumina. Finally, a comparison of the test results provided by three different methods proposed by different authors is presented. The tensile strength obtained from the three such methods on the same specimens provides contrasting results. Mean values vary from one method to another but the trends are similar for two of the methods. The third method gives less scatter, though the mean values obtained are lower and do not follow the same trend as the other methods for the different specimens