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Before Palm Pilots and iPods, PCs and laptops, the term \"computer\" referred to the people who did scientific calculations by hand. These workers were neither calculating geniuses nor idiot savants but knowledgeable people who, in other circumstances, might have become scientists in their own right. When Computers Were Human represents the first in-depth account of this little-known, 200-year epoch in the history of science and technology. Beginning with the story of his own grandmother, who was trained as a human computer, David Alan Grier provides a poignant introduction to the wider world of women and men who did the hard computational labor of science. His grandmother's casual remark, \"I wish I'd used my calculus,\" hinted at a career deferred and an education forgotten, a secret life unappreciated; like many highly educated women of her generation, she studied to become a human computer because nothing else would offer her a place in the scientific world. The book begins with the return of Halley's comet in 1758 and the effort of three French astronomers to compute its orbit. It ends four cycles later, with a UNIVAC electronic computer projecting the 1986 orbit. In between, Grier tells us about the surveyors of the French Revolution, describes the calculating machines of Charles Babbage, and guides the reader through the Great Depression to marvel at the giant computing room of the Works Progress Administration. When Computers Were Human is the sad but lyrical story of workers who gladly did the hard labor of research calculation in the hope that they might be part of the scientific community. In the end, they were rewarded by a new electronic machine that took the place and the name of those who were, once, the computers.

This study numerically demonstrates the light absorption spectra of each base of DNA-wrapped single-walled carbon nanotubes (SWCNTs). Previous experimental and theoretical studies show that the optical properties of these composites are different from the bare SWCNTs. In this work, we investigated the bases of DNA that influence optical properties. To obtain stable molecular states for studying optical properties, molecular dynamics calculations were performed. Additionally, light absorption spectra in the ultraviolet-to-near-infrared region of one type of base-wrapped (e.g., adenine-, thymine-, cytosine-, or guanine-wrapped) SWCNTs were investigated by utilizing the semi-empirical molecular orbital theory using SCIGRESS commercial software. This method can significantly reduce the calculation time compared to the ab initio molecular orbital method, making the handling of composites of bases and SWCNTs possible. We found that the largest peaks appear at a wavelength of around 300 nm for all the composites. Furthermore, we found that the light absorption spectra above 570 nm are strongly influenced by adenine and cytosine. Thus, our computational results provide insight into the optical properties and the effects of base–SWCNTs that are difficult to investigate experimentally under the influence of solvents and various molecules.

In order to have a stronger bond with the surrounding bone, the bone prosthesis needs to have interconnecting pores for bone cells to grow and more importantly to avoid stress shielding. At the same time, human bones have different composition and structure of bone tissue in different parts of the body due to different physical factors of the person, so the elastic modulus of the bones that need to be supported and replaced are not the same. And additive manufacturing has the advantages of rapid, efficient and precise manufacturing of complex shapes and high-quality three-dimensional structures, which can manufacture porous scaffold bone prosthesis, and achieve more accurate mechanical property requirements by controlling the design parameters. To study the effect of design strut length and design strut cross-section diameter size on the elastic modulus of tetrahedral titanium alloy scaffold unit, and with the help of UG NX, several digital models of porous titanium alloy scaffolds were constructed with the strut length and the strut cross-section diameter size as the parameters of variation, and then the elastic modulus of each porous titanium alloy scaffold was measured by ANSYS Workbench 2022, and the elasticity modulus of each porous titanium alloy scaffold was further derived from the relationship between the strut length and strut cross-section diameter size and the porous titanium alloy scaffold. Then the elastic modulus of each porous titanium alloy bracket was measured by ANSYS Workbench 2022, and the mathematical model between the strut length, strut cross-section size and elastic modulus of the porous titanium alloy bracket was further derived. Then, ANSYS Workbench 2022 was used to measure the elastic modulus of each porous titanium alloy bracket and further derive the mathematical model between strut length, strut cross-section diameter size and elastic modulus of the porous titanium alloy bracket, with the help of which the elastic modulus of the porous titanium alloy bracket with specific diameters and strut lengths was finally deduced to validate the correctness of the above predicted mathematical model, and to make reasonable explanations and corrections for the deviations. explanation and correction of deviations. As a result, the rapid prototyping technology can be used to design the required porous titanium alloy bracket in a more detailed way.

Currently, minimally invasive treatments that insert various treatment devices into an endoscope are actively being performed. A high-frequency (HF) snare is commonly used as an energy device inserted into an endoscope. However, using a high-frequency snare, problems usually occur, such as the obstruction of the visual field caused by smoke. On the other hand, microwave heating produces less smoke and provides a better visual field. In this study, a snare using microwave energy inserted into an endoscope is proposed, and its characteristics are evaluated.

In this paper, results of numerical simulations and measurements are presented concerning the non-uniform torsion and bending of an angled members of hollow cross-section. In numerical simulation, our linear-elastic 3D Timoshenko warping beam finite element is used, which allows consideration of non-uniform torsion. The finite element is suitable for analysis of spatial structures consisting of beams with constant open and closed cross-sections. The effect of the secondary torsional moment and of the shear forces on the deformation is included in the local finite beam element stiffness matrix. The warping part of the first derivative of the twist angle due to bimoment is considered as an additional degree of freedom at the nodes of the finite elements. Standard beam, shell and solid finite elements are also used in the comparative stress and deformation simulations. Results of the numerical experiments are discussed, compared, and evaluated. Measurements are performed for confirmation of the calculated results.

A measurement of b-hadron pair production is presented, based on a data set corresponding to an integrated luminosity of 11.4 fb-1 of proton-proton collisions recorded at √s = 8 TeV with the ATLAS detector at the LHC. Events are selected in which a bhadron is reconstructed in a decay channel containing J/ψ → µµ, and a second b-hadron is reconstructed in a decay channel containing a muon. Results are presented in a fiducial volume defined by kinematic requirements on three muons based on those used in the analysis. The fiducial cross section is measured to be 17.7 ± 0.1(stat.) ± 2.0(syst.) nb. A number of normalised differential cross sections are also measured, and compared to predictions from the Pythia8, Herwig++, MadGraph5 aMC@NLO+Pythia8 and Sherpa event generators, providing new constraints on heavy flavour production.

Mechanical behavior and energy evolution of rock around the tunnel are critical for evaluating the instability of geotechnical engineering. To reveal the influence of tunnel section shape on deformation, stress distribution, and fracturing mechanism of rock around the tunnel, a series of physical model shear tests for rock around prefabricated rectangular and circular tunnels were carried out, and corresponding fracturing and energy evolution analysis were also presented. In the shear test, the cracking evolution of rock around tunnel specimens was monitored and recorded by a high-speed camera and acoustic emission monitor to reveal the macro- and meso-fracture features. In addition, to examine the continuous-discontinuous shear process, four typical numerical models of rock around the tunnel were exploited to explore meso-mechanical behavior and fracturing mechanism. In light of the first law of thermodynamics, energy conversion process, damage characteristics and rockburst tendency of rock around tunnel specimens were investigated. The test results manifested that fracturing evolution, energy characteristic conversion, and micro-cracks evolution of rock around tunnel specimens generally were classified as four unified stages. In terms of fracturing evolution, rock around tunnel specimens experienced shearing compression stage (stage I), elastic stage (stage II) dominated by crack initiation, shearing fracture stage (stage III) dominated by crack propagation, coalescence and shear-induced rockburst, and shearing friction stage (stage IV). In the aspect of energy characteristic conversion, rock around tunnel specimens were mainly elastic deformation before peak shearing load, and the plastic deformation was relatively small. Partial dissipated strain energy acted on closing hole and crack initiation, and the rest was stored as elastic strain energy. After peak shearing load, the shear strength dropped rapidly, and a large amount of strain energy was converted into dissipated strain energy for crack propagation, coalescence and shear-induced rockburst. In the evolution of micro-cracks, the specimens underwent crack quiet period (stage I), crack initial increase stage (stage II), crack rapid increase stage (stage III), and crack stable stage (stage IV). Interestingly, the damage stress and rockburst tendency of rock around prefabricated rectangular tunnels were superior to those of rock around prefabricated circular tunnels, indicating that the bearing capacity of rock around prefabricated rectangular tunnels was superior to that of rock around prefabricated circular tunnels, related to the deviatoric stress distribution and confining pressure. In addition, a novel impact tendency index (Sp et) was presented for evaluating shear-induced rockburst tendency, which carved the proportional relationship between elastic strain energy and dissipative strain energy at peak shearing load. The research results were conducive to recognize the fracturing mechanism of rock around a tunnel subjected to shear condition and provided a theoretical basis for the prevention and control of geotechnical engineering.HighlightsShear characteristic, energy characteristic conversion and micro-cracks number evolution of rock around tunnel specimens generally were classified as four unified stages.Bearing capacity of rock around a prefabricated rectangular tunnel was superior to that of rock around a prefabricated circular tunnel, related to the deviatoric stress distribution and confining pressure.A novel damage variable was proposed to quantify the damage degree of rockA novel impact tendency index (Sp et) was presented for evaluating the shear-induced rockburst tendency

As a kind of water jet technology with strong impinging force and simple structure, the submerged impinging water jet can produce strong scouring action on subaqueous sediments. In order to investigate the flow field characteristics and impinging pressure of submerged impinging water jets at different impinging heights, the Wray-Agarwal (W-A) turbulence model is used for calculation. The velocity distribution and flow field structure at different impinging heights (1 ≤ H/D ≤ 8), and the impinging pressure distribution at the impingement plate under different Reynolds numbers (11, 700 ≤ Re ≤ 35100) are studied. The results show that with the increase of the impinging height, the diffusion degree increases and the velocity decreases gradually when the jet reaches the impingement region. The fluid accelerates first and then decelerates near the stagnation point. The maximum impinging pressure and the impinging pressure coefficient decrease with the increase of the impinging height, but the effective impinging pressure range remains unchanged. In this paper, the distribution characteristics of the impinging pressure in the region of the impingement plate at different heights are clarified, which provides theoretical support for the prediction method of the impinging pressure.

The collocation method is a widely used numerical method for science and engineering problems governed by partial differential equations. This paper provides a comprehensive review of collocation methods and their applications, focused on elasticity, heat conduction, electromagnetic field analysis, and fluid dynamics. The merits of the collocation method can be attributed to the need for element mesh, simple implementation, high computational efficiency, and ease in handling irregular domain problems since the collocation method is a type of node-based numerical method. Beginning with the fundamental principles of the collocation method, the discretization process in the continuous domain is elucidated, and how the collocation method approximation solutions for solving differential equations are explained. Delving into the historical development of the collocation methods, their earliest applications and key milestones are traced, thereby demonstrating their evolution within the realm of numerical computation. The mathematical foundations of collocation methods, encompassing the selection of interpolation functions, definition of weighting functions, and derivation of integration rules, are examined in detail, emphasizing their significance in comprehending the method’s effectiveness and stability. At last, the practical application of the collocation methods in engineering contexts is emphasized, including heat conduction simulations, electromagnetic coupled field analysis, and fluid dynamics simulations. These specific case studies can underscore collocation method’s broad applicability and effectiveness in addressing complex engineering challenges. In conclusion, this paper puts forward the future development trend of the collocation method through rigorous analysis and discussion, thereby facilitating further advancements in research and practical applications within these fields.

Globally, extensive land regions have fallen victim to coal mining subsidence, rendering the reuse of goaf sites a crucial concern. The residual deformation amount of these sites is the linchpin for determining their reusability. Presently, numerical computations of residual deformation in goafs, which overlook water-rock coupling, breed significant errors, posing severe threats to the safety of on-site structures. To remedy the situation, this research hinges on the mechanical experiment results of fractured rock masses under water-rock interaction within the goaf. By leveraging an embedded programming language, it pinpoints the irregular damage range of overlying strata due to water-rock effects. Then, corresponding mechanical parameters are allocated to the surrounding rocks at diverse spatial positions, with the erosive impact of water-soaked coal pillars also factored in. This gives rise to a novel numerical method that more precisely gauges groundwater’s influence on strata movement and surface subsidence. Using the 01 working face of a Shandong mine as a practical backdrop, the new method verifies its reliability and accuracy. When contrasted with traditional approaches, be it neglecting water filling or assuming full saturation in the goaf, it slashes the calculation error by 20%, furnishing new approaches for residual deformation calculation and novel perspectives for evaluating site stability under complex geological conditions.