omniomni/omni-engineering huggingface dataset:
With the development of internet and wireless technologies, location based search is among the most discussed topic in current era. To address issues of location based search a lot of research has been done but it mainly focused on the specific aspects of the domain like most of the studies focused, on the search of nearby restaurants, shopping malls, hospitals, stores etc., by utilizing location of users as searching criteria. Problem with these studies is that users might not be satisfied by their results and the sole reason behind this might be the absence of user p
— A model describing glitch disturbances is intro- duced and analysed. The model is used to find the response of glitch disturbances when adding a periodic dither to the input and applying low-pass filtering to the output. This averaged response is used to find a criterion to determine a sufficiently large dither amplitude that will make the averaged glitch disturbances appear as a constant on the output of the low- pass filter. An important resulting property is that the averaged response to glitch disturbances is independent of the model input. By fitting the model to the measured response of a common off-the-shelf digital-to-analogue converter, simulations are used to verify the analytical results. I. INTRODUCTION Glitches can be described as unwanted, transient distur- bances of short duration, often resembling spikes in a wave- form. As such, they are known to occur in e.g. multilevel power converters [1]–[3], systems with friction [4,5] and in digital-to-analogue converters [6]–[9]. In this paper, a glitch model is developed and analysed and applied and fitted to the response seen in a digital-to-analogue converter (DAC). For DACs, glitches are typically caused by timing mis- matches for transistor switching [6]–[9] and is a deterministic effect generated when a DAC switches between two output levels. Specifically, a glitch occurs when the analogue signal value corresponding to a given digital code appears before or after the signal value of the previous code disappears at the DAC output. The glitch properties of a DAC are often specified by the net area of the glitch impulse response [10] or sometimes by the area at the worst-case code transi- tion [11]. Fig. 1 illustrates deviations from ideal operation common in conventional DACs. The diagram shows the effects of a static non-linearity known as element mismatch or integral non-linearity (INL), as well as glitches of different severity. It should be noted that some non-ideal effects in DACs, including INL, can effectively be mitigated when the DAC is part of a closed-loop system. However, glitches will not be mitigated due to their wide-bandwidth, impulse-like behaviour, where most of the power in the disturbance is outside the bandwidth of the control law. Dither is a well-known method for static non-linear effects mitigation, including quantisation [12,13] and element mis- match [14]. Dynamic effects are also known to be mitigated in a similar fashion [4,15]; this effect has been demonstrated specifically for glitches [16]. Dither is a high-frequency Ahmad Faza’ ( ahmad.faza@uis.no ), Arnfinn A. Eielsen (eielsen@ux.uis.no ) are with the Dept. of Energy and Petroleum Engineering, University of Stavanger, Norway J. Leth ( jjl@es.aau.dk ) is with the Dept. of Electronic Systems, Automation & Control, Aalborg University, Denmark Ideal Real INL 010001010110011110001001101010111100 Minor GlitchMajor Glitch Fig. 1. Persistent non-linear deviations in conventional DACs including INL, and glitches. Where A+ i(A− i), indicate net areas of impulse responses for glitches due to
—Flux -pinned interfaces for spacecraft leverage the physics of superconductor interactions with electromagnetism to govern the dynamics between two bodies in close -proximity. Several unique advantages over traditional mechanical capture systems includ e robu stness to control failures, contactless reorientation of the capture target, and collision mitigation. This study describes a series of experiments performed in a microgravity environment during a parabolic -flight campaign to measure the dynamic behavior o f a flux -pinned interface in a flight -traceable environment. This paper presents the performance of a flux -pinned interface in the full six degrees of freedom in terms of several quantifiable metrics: success of capture at various energetic states, momentu m change , system damping, and interface stiffness of the two spacecraft bodies. TABLE OF CONTENTS 1. INTRODUCTION ................................ ............... 1 2. BACKGROUND ................................ ................. 2 3. METHODOLOGY ................................ .............. 2 4. DYNAMIC METRICS ................................ ........ 5 5. DYNAMICS CAPABILITIES .............................. 6 6. CONCLUSIONS ................................ ............... 11
Polymer porous membranes play a crucial role in various applications, including water filtration, tissue engineering, and drug administration. Conventional electrospinning is employed for the production of polymeric membranes because of its cost-effectiveness, scalability, and the flexibility. However, it has limitations in terms of controlling the form and size of the pores. Ensuring the ability to maintain a consistent and customizable pore size without sacrificing the thickness of the membrane becomes more crucial to satisfy the various requirements of cell and tissue engineering applications. To address these limitations, this work combines Near-Field Electrospinning with thermal treatment of polymer fibers and membranes by exploring the connection between polymer behavior, thermal effects, and capillary action by measuring the fluctuations in pore area under different temperatures and fiber spacings. Furthermore, the study investigated the influence of multilayer infusion on pore size and geometric arrangement by investigating multiple-layer configurations stacked at different angles. The results indicated that increasing layers leads to decreasing pore size, while the alignment of infused fibers adds to differences in pore form. By enabling enhanced control over membrane characteristics, the proposed approach can enhance the performance and consistency of polymer porous membranes in a wide range of applications. Keywords: Porous membrane, polymeric fiber, near-field electrospinning, thermal infusion, organ chip 1. Introduction Polymer porous membranes are widely used for their diverse applications, spanning water filtration [1-3], tissue engineering [4, 5], and drug delivery[6-8] due to their flexibility, biocompatibility, cost-effectiveness, and tunable mechanical characteristics. Specifically, creating controllable and uniform membrane pore sizes is the main focus for manufacturing membranes for multiple applications. For example, uniform pore sizes are crucial for ensuring consistent and predictable filtration performance in membrane-based separation processes. Irregular pore sizes can lead to uneven flow rates and reduced filtration efficiency, negatively impacting the membrane performance to separate particles based on size with high selectivity [9-11]. In drug delivery systems, uniform pore sizes play a crucial role in achieving precise control over the release rate of therapeutic agents, particularly in controlled-release formulations. The uniform pore structure of the membrane is essential for regulating drug release accurately and consistently. By maintaining well-defined pore size and distribution, the membrane can ensure a predictable and controlled release profile, enhancing the treatment's effectiveness. Uniform pores allow for steady and reproducible diffusion of the drug molecules through the membrane, minimizing variations in release kinetics and improving the overall performance of the drug delivery system. [12-15]. Furthermore, polymeric porous membranes are commonly used in tissue engineering, where scaffolds support cell growth and tissue regeneration [16-19]. Different cells exhibit distinct p
This paper evaluates perception of complexity in a novel explanatory model that relates product performance and engineering e ort. Complexity is an intermediate factor with two facets: it enables desired product performance but also requires e ort to achieve. Three causal mechanisms explain how exponential growth bias, excess complexity, and di erential perception lead to e ort overruns. Secondary data from a human subject experiment validates the existence of perception of complexity as a context-dependent factor that in uences required design e ort. A two-level mixed e ects regression model quanti es di erences in perception among 40 design groups. Results summarize how perception of complexity may contribute to e ort overruns and outline future work to further validate the explanatory model and causal mechanisms. 1 Introduction Complex engineering projects face a sustained risk of signi cant e ort overruns on cost and schedule. Overruns of 20{40% routinely occur across diverse domains such as defense ac- quisition (U.S. Government Accountability Oce, 2011), Earth and space science missions (National Research Council, 2010), software (Mol kken and J rgensen, 2003), and infras- tructure and public works projects (Flyvbjerg et al., 2002) and overruns exceeding 100% are not uncommon. E ort overruns destabilize planning exercises, generate waste from de- scoping or canceling programs, and generally threaten objectives that depend on timely and a ordable product deployment. The systems engineering and design community points to complexity as a technical driver for cost growth (Arena et al., 2008; Roberts et al., 2016). Existing literature describes and measures complexity as a nonfunctional attribute correlated with design e ort (Calvano and John, 2004; Sheard and Mostashari, 2009; ElMaraghy et al., 2012). However, this analytical perspective leaves a gap to understand how underlying socio-technical mechanisms contribute to e ort expenditures and overruns in system design. For example, Flyvbjerg et al. (2009) explains overruns in infrastructure projects through human factors of delusion and deception rather than complexity itself. Delusion arises from 1 errors in heuristics or biases associated with human decision making. The planning fal- lacy tends to underestimate task completion times even when past estimates are known to be overly optimistic. Similarly, the anchoring and adjustment e ect biases estimates by focusing on the rst possible value and only considering insucient adjustments from it. Deception arises from awed decision-making practices that reinforce localized objectives. The principal-agent problem considers misaligned behavior between the principal responsible for a decision and the agent acting on his or her behalf where issues such as self-interest, asymmetric information, accountability, and risk p
Scientific aspects of fire and smoke hazards associated with batteries were introduced in this talk. Counterfeit batteries in used cars have to be watched as t he consequence is more hazardous than genuine batteries. Fire protection should be enhanced. 1. Introduction Different electrical batteries are widely used in many areas for necessity and sustainable environment. Lithium -ion batteries h ave high efficiency and long service life, and thus have led to many new applications including el ectric vehicles and building s. Basic physics why and how it is possible to have high energy capacity in lithium -ion batteries will be briefed. Such heating might give thermal hazards . Fire or even explosion start ed from batteries always occurred. Scientific aspects of those hazards are pointed out in this talk for the society, particularly the authority handling fire safety, to explore in practical engineering applications. Studies on fire hazards were focused on t he starting fire of igniting a battery. Consequences of burning the combustibles inside should be watched. Smoke toxicity to human was ignored. Another key point is using too many counterfeit batteries with unknown materials and construction. Risk paramete rs are not available for the counterfeit batteries. Correlations for risk parameters such as time to ignition or heat release rates with battery capacity deduced for genuine batteries are not applicable. 2 2. Lithium -ion Battery ? The basic physics why and how it is possible to have high energy capacity in lithium -ion batteries was explained [1] . However, heating has been a common problem . Without appropriate design, they might give fire and explosion as reported. 3. Big Starting Fire Source Easy to Ignite As explained earlier on the basic physics, heating effect might give adverse effects. Any thermal generating effect without lost can accumulate to heat up the combustibles to ignite, particularly the electrolytes as reviewed above. A fire is resulted when heat lost is low. Further, electrolytes as condensed matter would be transited to gas, heating up and generat e pressure to give explosion. A big ignition source with the heat release rate curve upon burning a car is recorded as in Fig. 1. Upon igniting the battery at TTI B, the car ignited with TTI Car. Must do something to delay TTI Car. Fig. 1: Battery – A big ignition source Heat release rate 3 4. Literature Key
Polluted water has many pollutants contributing to its state, one of the major being heavy metals like lead, cadmium, chromium etc. This paper focuses on the removal of chromium by adsorption on local soils, since chromium is among the toxic pollutants, since the pollutant on reaching into the human body has proven to be carcinogenic. Chromium is released as wast e from mainly tanning, metal finishing industries etc. Chromium exists in different oxidation states and Cr+6 being the pre-dominant. The temporary and permanent health hazards include diarrhea, stomach and intestinal bleeding, cramps in liver and in some cases even kidney damage. The different codes and standards define the permissible limits of chromium in drinking water. Since its permissible limits are necessary to assess the degree of pollution and treatment that is to be given. Since the leachate from the waste on transferring on to the landfill must not percolate via the compacted layers and testing of soils for its adsorption capacity becomes a major concern since the water table will be contaminated and therefore urges for a material that is locally available and can be used as filler material in landfills that can withheld the oozing of the contaminant (i.e. better adsorption capacity of the soil) as well as the leachate intercepting the streams during wet season. The steps to be followed to conduct this observation mainly include study of soil properties, preparation of standard/stock solution and the method of analysis. The method that is adopted for adsorption of Chromium includes Batch test and Column test with the arrival of the results with its reference to the isotherms that are drawn from the experimental results. The maximum percentage removal of chromium occurs at the adsorbent depth of 30cm and occurs maximum for 4ppm, i.e. 31.25%. TABLE OF CONTENTS CHAPTER NO PARTICULARS PAGE NO. LIST OF TABLES I LIST OF CHARTS II LIST OF IMAGES III LIST OF ABBREVIATIONS IV 1 INTRODUCTION 1 1.1 GENERAL 2 1.2 NEED FOR THE STUDY 4 2 STUDY OF ADSORPTION 6 2.1 THEORY OF ADSOPRTION 7 2.2 MECHANISM 8 2.3 PROPERTIES OF ADSORBENT 9 2.4 FACTORS INFLUENCING ADSORPTION 9 2.5 APPLICATIONS 10 2.6 ANALYSIS OF ADSORPTION. 10 2.6.1 FREUNDLICH ISOTHERMS 11 2.6.2 LANGMUIR ISOTHERMS 12 3 LITERATURE SURVEY 13 3.1 STUDIES ON ADSORPTION OF CHROMIUM (VI) 14 CHAPTER NO PARTICULARS PAGE NO. 3.2 COLUMN STUDY 15 4 MATERIALS AND METHODOLOGY 21 4.1 GENERAL 22 4.2 MATERIALS AND APPARATUS 22 4.3 PROCEDURE 29 4.3.1 COLUMN TEST 29 5 RESULTS 31 5.1 RESULTS OF COLUMN STUDY 32 5.2 COMMENTS 41 6 CONCLUSION 42 6.1 OVERVIEW 43 6.2 PARAMETERS 44 6.3 FUTURE SCOPE 45 7
We deduce from the second Newton’s law the medium constitute O hm’s law for an electrical ﬂow in a medium with square power law for the condu ctor resistivity. Key words: Non-Linear Ohm’s Law. (1)– Bolsista de P´ os Doutoramento Sˆ enior – (CNPq) (2)– Professor Colaborador–Aposentado 1 The elementary and phenomonogical discussions of the elect rical conductivity in medi- ums without recourse to Quantum Mechanics always have been m ade in a context where the eﬀective medium resistence has an eﬀective behavior of a linear damping term pro- portional to the ﬂow’s velocity ([1],[2]). In this pedagogi cal comment we present an elementary approach on electrical conductivities in a medi um with a non-linear quadratic polinomial damping term on the electron ﬂow velocities [3]. Let us star our analysis from the second Newton’s law applied t o a one-dimensional electron ﬂow through a conductor with a square power law for t he conductor resistence under the presence of a steady electric ﬁeld (electron mass me= 1) dV dτ=eE−νV2(1) V(0) = 0 (2) hereV(τ) is the one-dimensional electron velocity and I(τ) =ρAV(τ) is the current ﬂow whereAis the normal cross section of the conduction and ρis the electron charge density. The solution of the Riccati equation (1) can be obtained thro ugh the substitution V(t) =1 νdy(t)/dt y(t)(3) withy(t) satisfying the linear equation d2y(t) dt2−(νeE)y(t) = 0 y(0) =y0;y′(0) = 0 (4) the solution of eq.(4) is easily given by y(t) =c1e/parenleftbig√ eνE/parenrightbig t+c2e−/parenleftbig√ eνE/parenrightbig t(5) By performing the inverse transformation in eq.(3) we obtai n the physical electron ﬂow velocity V(τ) =/radicalbigg eE ν 1−e−2/parenleftbig√ eνE/parenrightbig t 1+e−2/parenleftbig√ eνE/parenrightbig t  (6) In a steady-state processes (the asymptotic t→ ∞limit), we get: Vs=/radicalbigg eE ν(7) 2 and leading, thus, to the non-linear Ohm’s law (note that E=/hatwideV/d), namely I=ρA/radicalBigg e/hatwideV νd(8-a) or /hatwideV=I2¯R (8-b) with the eﬀective electrical resistance ¯R=νd ρ2A2e(9) At this point and just for completeness let us analyze the mor e general case with the microscopic friction law αV+νV2(αandνpositive constants): dV(τ) dτ=eE−αV−νV2(10) V(0) = 0 (11) By performing the Riccati transformation (3) in eq.(9) we ob tain d2y(τ) dτ2+αdy(τ) dτ−(eEν)y(τ) = 0 (12) withy(0) =y0andy′(0) = 0. As a consequence we have the result V(τ) =α 2ν(γ−1)/bracketleftbigg1−Aeαγτ 1+Aeαγτ/bracketrightbigg (13) Hereγ=/parenleftbigg 1+4eνE α2/parenrightbigg1/2 andAis a constant. The steady solution is thus given by the τ→ ∞limit in the above equation Vc=α 2ν(γ−1) =1 ν/bracketleftBigg −α 2+α 2/radicalbigg 1+4eνE α2/bracketrightBigg (14) and thus, giving the associated non-linear Ohm’s law ¯I=ρA να 2/bracketleftBigg −1+/radicalbigg +1+4eνE α2/bracketrightBigg (15) 3 or to the generalization of eq(8-b): /hatwideV=/parenleftbiggαd ρAe/parenrightbigg ¯I+/parenleftbiggνd ρ2A2e/parenrightbigg ¯I2(16) Acknowledgements: Luiz C.L. Botelho is thankful to professor Helayel Netto (DCP- CBPF) for support.
e Keywords Graphene, Cold welding, Heat treatment, Experiment. Introduction The design is based on few assumptions such as cold welding of graphene parts that are scrapped off graphite can induce outer valence electrons into required state and further heat treatment can help with creating one sheet out of two. Figure 1 depicts the arms moving sheet of graphene over another with preferably similar boundary to minimize defects in end product. Figure 1 The flow diagram below depicts the experiment concept: Check graphene sheet specimens for boundary defects Bring two graphene sheets within a suitable distance parallel to each other on same planeThis paper documents the concept of an experiment designed to test the possibility of graphene sheet generation through cold welding and/or heat treatment and is based on certain assumptions and creative ignorance.Conception of experiment to generate graphene sheets through cold welding Geim, A K (2012). "Graphene prehistory" . Physica Scripta. 146: 014003. Bibcode:2012PhST..146a4003G . doi:10.1088/0031-8949/2012/T146/014003 . Boehm, H.P; Setton, R; Stumpp, E (1986). "Nomenclature and terminology of graphite intercalation compounds". Carbon. 24 (2): 241. doi:10.1016/0008-6223(86)90126-0 .Apply vacuum, heat-treatment , voltage.Observe end result Change distance/voltage/heat The experiment draws inspiration from simplicite graphene manufacturing process and builds on the literature gap on excitation of individual atoms at the boundry of graphene sheets removed from graphite to ease joining to separate sheet which further can be modularized and repeated over and over again to gain better yield sheets while having a trade with defects at joining of boundaries and boundary tension such as hsown in figure 2 below.
Thermogravimetric analysis (TGA) is one of the most popular analysis techniques to study the decomposition process of polymeric materials in controlled atmospheres at various temperatures. In this review, dynamic TGA was carried out to determine the thermal stability of the recycled epoxy-based and vinyl ester-based carbon fiber composite (CFC). The specimens were heated from ambient to 800°C under nitrogen and air at different heating rates. Results indicates that different heating rates has no significant influence on the degradation of the epoxy-based CFC. Keywords: Recycling; TGA; Carbon fiber composite This work is licensed under Creative Commons Attribution 4.0 License AJES.MS.ID.000508. Academic Journal of Engineering Sciences Citation: Seyed Hossein Mamanpush, Reyhaneh Tavousi Tavousi, Bahareh Tavousi Tabatabaei. Dynamic Thermogravimetric Analysis of Recycled Carbon Fiber Composites: Mini Review Acad J Eng Sci. 1(2): 2018. AJES.MS.ID.000509.Page 2 of 2vinyl ester-based CFC material shows the residue around 77% that remained, this can be assigned to the carbon fiber content of the sample [12]. Comparing the TGA results of recycled epoxy-based CFC and vinyl ester-based CFC shows that there is no significant difference between degradation behavior of them. The TGA results of recycled CFCs in air show that recycled vinyl ester-based CFC have better thermal stability comparing to epoxy-based CFCs. At 800°C the TGA results of recycled vinyl ester-based CFC material shows the residue around 59% that remained, and results of recycled epoxy-based CFC material shows the residue around 0%, it shows the significant thermal stability of vinyl ester-based CFC in air. Figure 3: Dynamic TGA curve recorded in Air at heating rate of 20°C min-1. Figure 4: Dynamic TGA curve recorded in Air at heating rate of 20°C min -1. Conclusion Recycled CFCs are a viable material for making second generation composites. The obtained results from dynamic TGA of recycled carbon fiber composite materials demonstrate that recycled CFCs have superior thermal stability. Results indicates that different heating rates has no significant influence on the degradation of the epoxy-based CFC. Acknowledgement None. Conflict of Interest No Conflict of Interest.