Friday, January 29, 2010
Most Influential Scientists - Published February 24, 2009 by Mongoose
This is part one of what will be a two part series on the most influential scientists in history. While these are not technically the “greatest” scientists, there is bound to be some overlap as the contributions that many of these men and women made to science are among the most important.
10 Marie Curie 1867 – 1934
“One never notices what has been done; one can only see what remains to be done.”
Polish physicist and chemist, Marie Curie was a pioneer in the field of radioactivity, the only person honored with Nobel Prizes in two different sciences, and the first female professor at the University of Paris. She founded the Curie Institutes in Paris and Warsaw. Her husband Pierre Curie was also a Nobel laureate, as were her daughter Irene Joliot-Curie and son-in-law Frederic Joliot-Curie. Her achievements include the creation of a theory of radioactivity (a term coined by her), techniques for isolating radioactive isotopes, and the discovery of two new elements, radium and polonium. It was also under her personal direction that the world’s first studies were conducted into the treatment of neoplasms (“cancers”), using radioactive isotopes. While an actively loyal French citizen, she never lost her sense of Polish identity. She named the first new chemical element that she discovered (1898) “polonium” for her native country, and in 1932 she founded a Radium Institute in her hometown Warsaw, headed by her physician-sister Bronisława.
7 Max Planck 1858 – 1947
“We have no right to assume that any physical laws exist, or if they have existed up to now, that they will continue to exist in a similar manner in the future.”
Max Planck, a German physicist, is considered to be the founder of quantum theory, and one of the most important physicists of the twentieth century. Planck made many contributions to theoretical physics, but his fame rests primarily on his role as originator of the quantum theory. This theory revolutionized our understanding of atomic and subatomic processes, just as Albert Einstein’s theory of relativity revolutionized our understanding of space and time. Together they constitute the fundamental theories of 20th-century physics. His discoveries have led to industrial and military applications that affect every aspect of modern life.
6 Charles Darwin 1809 – 1882
“I love fools’ experiments. I am always making them.”
English naturalist and biologist, Darwin demonstrated that all species of life have evolved over time from common ancestors through the process he called natural selection. The fact that evolution occurs became accepted by the scientific community and the general public in his lifetime, while his theory of natural selection came to be widely seen as the primary explanation of the process of evolution in the 1930s, and now forms the basis of modern evolutionary theory. In modified form, Darwin’s scientific discovery remains the foundation of biology, as it provides a unifying logical explanation for the diversity of life. His 1859 book On the Origin of Species established evolution by common descent as the dominant scientific explanation of diversification in nature. He also examined human evolution and sexual selection in The Descent of Man, and Selection in Relation to Sex, followed by The Expression of the Emotions in Man and Animals. In recognition of Darwin’s pre-eminence, he was one of only five 19th century UK non-royal personages to be honored by a state funeral.
5 Leonardo da Vinci 1452 – 1519
“Anyone who conducts an argument by appealing to authority is not using his intelligence; he is just using his memory.”
Leonardo da Vinci was an Italian polymath. He was an expert mathematician, engineer, inventor, anatomist, painter, sculptor, architect, botanist, musician and writer. Leonardo has often been described as the archetype of the “Renaissance man”, a man whose seemingly infinite curiosity was equalled only by his powers of invention. Leonardo is revered for his technological ingenuity. He conceptualized a helicopter, a tank, concentrated solar power, a calculator, the double hull and outlined a rudimentary theory of plate tectonics. Relatively few of his designs were constructed or were even feasible during his lifetime, but some of his smaller inventions, such as an automated bobbin winder and a machine for testing the tensile strength of wire, entered the world of manufacturing unheralded. As a scientist, he greatly advanced the state of knowledge in the fields of anatomy, civil engineering, optics, and hydrodynamics.
4 Galileo Galilei 1564 – 1642
“All truths are easy to understand once they are discovered; the point is to discover them.”
Galileo was an Italian physicist and astronomer. His achievements include improvements to the telescope and consequent astronomical observations, and support for Copernicanism. Galileo has been called the “father of modern observational astronomy”, the “father of modern physics”, the “father of science”, and “the Father of Modern Science.” The motion of uniformly accelerated objects, taught in nearly all high school and introductory college physics courses, was studied by Galileo as the subject of kinematics. His contributions to observational astronomy include the telescopic confirmation of the phases of Venus, the discovery of the four largest satellites of Jupiter, named the Galilean moons in his honor, and the observation and analysis of sunspots. Galileo also worked in applied science and technology, improving compass design. Galileo’s championing of Copernicanism was controversial within his lifetime. The geocentric view had been dominant since the time of Aristotle, and the controversy engendered by Galileo’s presentation of heliocentrism as proven fact resulted in the Catholic Church’s prohibiting its advocacy because it was not empirically proven at the time. Galileo was eventually forced to recant his heliocentrism and spent the last years of his life under house arrest on orders of the Holy Inquisition.
2 Albert Einstein 1879 – 1955
“A man should look for what is, and not for what he thinks should be.”
Einstein, a German physicist, is best known for his theory of relativity and specifically mass–energy equivalence, expressed by the equation E = mc2. Einstein received the 1921 Nobel Prize in Physics “for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect. Einstein’s many contributions to physics include his special theory of relativity, which reconciled mechanics with electromagnetism, and his general theory of relativity, which was intended to extend the principle of relativity to non-uniform motion and to provide a new theory of gravitation. His other contributions include advances in the fields of relativistic cosmology, capillary action, critical opalescence, classical problems of statistical mechanics and their application to quantum theory, an explanation of the Brownian movement of molecules, atomic transition probabilities, the quantum theory of a monatomic gas, thermal properties of light with low radiation density (which laid the foundation for the photon theory), a theory of radiation including stimulated emission, the conception of a unified field theory, and the geometrization of physics. Einstein published over 300 scientific works and over 150 non-scientific works. The physics community reveres Einstein, and in 1999 Time magazine named him the “Person of the Century”. In wider culture the name “Einstein” has become synonymous with genius.
1 Isaac Newton 1643 – 1727
“To myself I am only a child playing on the beach, while vast oceans of truth lie undiscovered before me.”
Newton was an English physicist, mathematician, astronomer, natural philosopher, alchemist, theologian and one of the most influential men in human history. His Philosophiæ Naturalis Principia Mathematica, published in 1687, is considered to be the most influential book in the history of science.
In this work, Newton described universal gravitation and the three laws of motion, laying the groundwork for classical mechanics, which dominated the scientific view of the physical universe for the next three centuries and is the basis for modern engineering.
Newton showed that the motions of objects on Earth and of celestial bodies are governed by the same set of natural laws by demonstrating the consistency between Kepler’s laws of planetary motion and his theory of gravitation, thus removing the last doubts about heliocentrism and advancing the scientific revolution.
In mechanics, Newton enunciated the principles of conservation of momentum and angular momentum. In optics, he built the first “practical” reflecting telescope and developed a theory of color based on the observation that a prism decomposes white light into a visible spectrum. He also formulated an empirical law of cooling and studied the speed of sound. In mathematics, Newton shares the credit with Gottfried Leibniz for the development of the differential and integral calculus. He also demonstrated the generalized binomial theorem, developed the so-called “Newton’s method” for approximating the zeroes of a function, and contributed to the study of power series. Newton’s stature among scientists remains at the very top rank, as demonstrated by a 2005 survey of scientists in Britain’s Royal Society asking who had the greater effect on the history of science, Newton was deemed much more influential than Albert Einstein.
Saturday, January 23, 2010
Why ANSYS and not Abaqus?
In complex problems like blasting, analytical solutions are extremely hard to obtain. Thus, numerical methods must be employed. AUTODYN, LS-DYNA and Abaqus are all general-purpose finite element analysis (FEA) software, which are the suitable alternative choices. A brief discussion of each of this software is given.
ANSYS was created in 1970 by Dr. John Swanson (Swanson Analysis Systems, Inc.). ANSYS version 12 is used in our project. ANSYS Multiphysics software are non exportable analysis tools incorporating pre-processing (geometry creation, meshing), solver and post-processing modules in a graphical user interface (GUI).
ANSYS AUTODYN software is an explicit analysis tool, which is especially suited to the solution of interaction problems of different systems of structures, fluids and gases together as found in blast applications. AUTODYN software allows different solvers such as Lagrange and Euler to be used together in the same model. Users of ANSYS AUTODYN are able to complete simulation projects with significantly less effort, less time and lower total cost. The high productivity is a result of the easy to use, quick to learn intuitive, interactive graphical interface implemented in ANSYS AUTODYN. Additional time and effort savers in problem set-up and analysis are provided by automatic options to define contact, coupling interfaces and minimizing input requirements with the use of safe logical defaults.
Likewise LS-DYNA (by Livermore SoftwareTechnology Corporation) is also capable of simulating complex real world problems. Its core-competency is in highly nonlinear transient dynamic finite element analysis (FEA) using explicit time integration. LS-DYNA comes with LS-PrePost and LS-OPT. LS-PrePost is an advanced interactive program for preparing input data for LSDYNA and processing the results from LSDYNA analyses. LS-OPT allows the user to structure the design process, explore the design space and compute optimal designs according to the specified constraints and objectives.
With collaborative effort between ANSYS and Livermore Software Technology Corporation, the ANSYS LS-DYNA was developed in 1996. Because ANSYS LS-DYNA is created from the same powerful technology as ANSYS, it is easy to combine with other ANSYS products. So both AUTODYN and LS-DYNA are parts of the full version of ANSYS Multiphysics.
The other powerful finite element analysis software, which is popular with academic and research institutions is the Abaqus. This is a commercial software package developed by HKS Inc of Rhode Island, USA. The Abaqus product suite consists of three core products: Abaqus/Standard, Abaqus/Explicit and Abaqus/CAE. Abaqus/Standard is a general-purpose solver using a traditional implicit integration scheme to solve finite element analyses. Abaqus/Explicit uses an explicit integration scheme to solve highly nonlinear transient dynamic and quasi-static analyses. Abaqus/CAE provides an integrated modeling (preprocessing) and visualization (post processing) environment for the analysis products. The Abaqus products use the open-source scripting language Python for scripting and customization. Abaqus/CAE uses the fox-toolkit for GUI development. Abaqus is used in the automotive, aerospace, and industrial product industries.
Both ANSYS and Abaqus are powerful FEA software and either of them could serve our purpose in our project. Nonlinear analyses in both packages are extremely powerful. Both has flexibility i.e. the programs can be adapted to your specific needs. Both packages offer 64-bit software at no extra charge. ANSYS' support is through their Value Added Sellers (VARs) whereas Abaqus' support is direct. But both packages offer good support. However, there are some minor differences between the two which are listed below:
1. ANSYS is more easy to use than Abaqus. In particular the ANSYS Workbench is preferred by engineers and the industry people because it is easier to use. ANSYS does not require users that necessarily understand either mechanics or finite elements. On the other hand, Abaqus is less user friendly than ANSYS and needs a deeper understanding of mechanics and finite elements.
Most engineers in the field have no use for nonlinear mechanics and have very little understanding of material behaviors beyond linear elastic. Material data are also hard, if not impossible, to get. So, even if a problem is best tackled by an advanced material model, the prudent choice is to go linear elastic, linear buckling etc. That is something ANSYS does well with minimal user input; no mesh generation hassles, complex geometries easily handled, etc. It seems ABAQUS is more popular with academic and research institutions, perhaps due to the wide material modeling capability, and the program's ability to be customized.
2. Although both packages are similar in capabilities but Abaqus is more expensive than ANSYS. In addition, the Abaqus software is licensed on an annual basis. A renewal fee has to be paid each year. ANSYS supports multiple processors at no extra charge, but Abaqus only supports running on a single processor unless you purchase an add-on which will allow you to take advantage of multiple processor on one or more machines (distributed computing).
3. Some users suggested that ANSYS’s GUI (especially the geometry input) is better than that in Abaqus. In addition, ANSYS uses APDL (ANSYS Parametric Design Language), which is more intuitive scripting language than python (open-source scripting language) used in that Abaqus. Since ANSYS is more user-friendly, it has more users than the Abaqus. So ANSYS skills may be more re-usable.
For the reasons given above, we will use ANSYS AUTODYN, instead of Abaqus.
Tuesday, January 12, 2010
Typical CIU Triaxial Compression Test
Isotropically Consolidated Undrained (CIU) Triaxial Compression Test
Summary
CONSOLIDATION STAGE
SHEARING STAGE
Stress - strain relationship
Pore pressure change during shearing
Mohr Circle
Geotechnical Quotes from Karl von Terzaghi, the father of soil mechanics
Karl von Terzaghi (October 2, 1883 – October 25, 1963) was an Austrian civil engineer and geologist, called the father of soil mechanics. Here are some of his quotes.
“Unfortunately, soils are made by nature and not by man, and the products of nature are always complex… As soon as we pass from steel and concrete to earth, the omnipotence of theory ceases to exist. Natural soil is never uniform. Its properties change from point to point while our knowledge of its properties are limited to those few spots at which the samples have been collected. In soil mechanics the accuracy of computed results never exceeds that of a crude estimate, and the principal function of theory consists in teaching us what and how to observe in the field.”
“When utilizing past experience in the design of a new structure we proceed by analogy and no conclusion by analogy can be considered valid unless all the vital factors involved in the cases subject to comparison are practically identical. Experience does not tell us anything about the nature of these factors and many engineers who are proud of their experience do not even suspect the conditions required for the validity of their mental operations. Hence our practical experience can be very misleading unless it combines with it a fairly accurate conception of the mechanics of the phenomena under consideration.”
“…once a theory appears on the question sheet of a college examination, it turns into something to be feared and believed, and many of the engineers who were benefited by a college education applied the theories without even suspecting the narrow limits of their validity.”
“… Any attempt to stop the settlement without making the proposed preliminary investigation would be an irresponsible gamble. Since I have witnessed many gambles of this kind I can state from personal experience that the savings associate with inadequate preliminary investigations are entirely out of proportion to the financial risks.”
“These government organizations have a great reluctance to carry responsibilities; they always want to be covered by something, and a factor of safety-that is something tangible. So when the general asks the captain: ”How about the factor of safety of the dam?-“1.51” [is the answer] and then he is happy”
“The one thing an engineer should be afraid of is the development of conditions on the job which he has not anticipated. The construction drawings are no more than a wish dream. I have the impression that the great majority of dam failures were due to negligent construction and not to faulty design.”
“Soil Mechanics arrived at the borderline between science and art. I use the term “art” to indicate mental processes leading to satisfactory results without the assistance of step-for-step logical reasoning…To acquire competence in the field of earthwork engineering one must live with the soil. One must love it and observe its performance not only in the laboratory but also in the field, to become familiar with those of its manifold properties that are not disclosed by boring records…” 4th International Congress on Soil Mechanics, England , 1957
“I produced my theories and made my experiments for the purpose of establishing an aid in forming a correct opinion and I realized with dismay that they are still considered by the majority as a substitute for common sense and experience.”
When Yves Lacroix asked Terzaghi how much time he ought to spend on writing his report, he got the following advice:
“Spend on it as much time as necessary to inform the reader with as few words as practicable about all the significant findings and about the essential features of the construction operations which have been performed”
“Proving the old adage that results depend not on the perfection of the equipment but on the truth of the proposition… The simper and cheaper the apparatus, the better it expresses the purpose and accordingly one can gain insight into a process being investigated, approving or rejecting and postulating anew, without wasting time and money. Costly, sensitive instruments belong to the situation where one already has a clear hold of the natural phenomena and where there is value in obtaining refined numbers. When one begins experiments with costly apparatus, he becomes a slave to that apparatus and the experiment, rather than serving to establish the truthfulness of a valuable idea, serves merely to establish a fact-but never to establish a law.”
“Theory is the language by means of which lessons of experience can be clearly expressed.”
“Theory -and even very rigorous theory- is required for training and developing our capacity for correctly interpreting what we observe; but at the same time, with theory alone we could not accomplish anything at all in the field of earthwork engineering, an the more plain facts we can accumulate, the better. I always lose my temper with people who think they have grasped the very core of the substance after they have succeeded in representing some artificially simplified phase of it by means of complicated triple integrals; while at the same time, they have forgotten how the soil really looks. Keen observation is at least as necessary as penetrating analysis”
“Unfortunately, soils are made by nature and not by man, and the products of nature are always complex… As soon as we pass from steel and concrete to earth, the omnipotence of theory ceases to exist. Natural soil is never uniform. Its properties change from point to point while our knowledge of its properties are limited to those few spots at which the samples have been collected. In soil mechanics the accuracy of computed results never exceeds that of a crude estimate, and the principal function of theory consists in teaching us what and how to observe in the field.”
“When utilizing past experience in the design of a new structure we proceed by analogy and no conclusion by analogy can be considered valid unless all the vital factors involved in the cases subject to comparison are practically identical. Experience does not tell us anything about the nature of these factors and many engineers who are proud of their experience do not even suspect the conditions required for the validity of their mental operations. Hence our practical experience can be very misleading unless it combines with it a fairly accurate conception of the mechanics of the phenomena under consideration.”
“…once a theory appears on the question sheet of a college examination, it turns into something to be feared and believed, and many of the engineers who were benefited by a college education applied the theories without even suspecting the narrow limits of their validity.”
“… Any attempt to stop the settlement without making the proposed preliminary investigation would be an irresponsible gamble. Since I have witnessed many gambles of this kind I can state from personal experience that the savings associate with inadequate preliminary investigations are entirely out of proportion to the financial risks.”
“These government organizations have a great reluctance to carry responsibilities; they always want to be covered by something, and a factor of safety-that is something tangible. So when the general asks the captain: ”How about the factor of safety of the dam?-“1.51” [is the answer] and then he is happy”
“The one thing an engineer should be afraid of is the development of conditions on the job which he has not anticipated. The construction drawings are no more than a wish dream. I have the impression that the great majority of dam failures were due to negligent construction and not to faulty design.”
“Soil Mechanics arrived at the borderline between science and art. I use the term “art” to indicate mental processes leading to satisfactory results without the assistance of step-for-step logical reasoning…To acquire competence in the field of earthwork engineering one must live with the soil. One must love it and observe its performance not only in the laboratory but also in the field, to become familiar with those of its manifold properties that are not disclosed by boring records…” 4th International Congress on Soil Mechanics, England , 1957
“I produced my theories and made my experiments for the purpose of establishing an aid in forming a correct opinion and I realized with dismay that they are still considered by the majority as a substitute for common sense and experience.”
When Yves Lacroix asked Terzaghi how much time he ought to spend on writing his report, he got the following advice:
“Spend on it as much time as necessary to inform the reader with as few words as practicable about all the significant findings and about the essential features of the construction operations which have been performed”
“Proving the old adage that results depend not on the perfection of the equipment but on the truth of the proposition… The simper and cheaper the apparatus, the better it expresses the purpose and accordingly one can gain insight into a process being investigated, approving or rejecting and postulating anew, without wasting time and money. Costly, sensitive instruments belong to the situation where one already has a clear hold of the natural phenomena and where there is value in obtaining refined numbers. When one begins experiments with costly apparatus, he becomes a slave to that apparatus and the experiment, rather than serving to establish the truthfulness of a valuable idea, serves merely to establish a fact-but never to establish a law.”
“Theory is the language by means of which lessons of experience can be clearly expressed.”
“Theory -and even very rigorous theory- is required for training and developing our capacity for correctly interpreting what we observe; but at the same time, with theory alone we could not accomplish anything at all in the field of earthwork engineering, an the more plain facts we can accumulate, the better. I always lose my temper with people who think they have grasped the very core of the substance after they have succeeded in representing some artificially simplified phase of it by means of complicated triple integrals; while at the same time, they have forgotten how the soil really looks. Keen observation is at least as necessary as penetrating analysis”
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