New Developments in Geotechnical Earthquake Engineering

Based on the review on the advances of several important problems in geotechnical seismic engineering, the authors propose the initial analysis theory of time-frequency-amplitude (known as TFA for short), in an effort to realize the organic combination of time and frequency information and develop a groundbreaking concept to the traditional idea in the geotechnical seismic engineering area

A novel approach for seismic design of anchored sheet pile wall

Istraživanja oštećenih zemljanih konstrukcija nakon zemljotresa pokazala su da je ukotvljeni priboj (zagat) odlična seizmička konstrukcija. Međutim, zbog složenosti sustava naprezanja, neka temeljna teorijska pitanja još nisu potpuno riješena te teorijski razvoj konstrukcije zaostaje za primjenom, posebice u razvoju teorije seizmičkog proračuna. Kako bi se nadoknadio ovaj nedostatak, u radu se predlaže novi pojednostavljeni pristup, temeljen na prethodnom istraživanju. U tom se pristupu razmatrao učinak dinamičke sprege stup (pilon, šip) – zemlja – anker (zatezač), a postavljene su i odgovarajuće jednadžbe. Uz to, kako bi se provjerila primjenjivost predloženog pristupa, provedena su opsežna ispitivanja trešenjem (shaking table tests). U tim su ispitivanjima odgovarajuće primijenjeni omjeri sličnosti i slični materijali, a podaci o vremenu horizontalnog i vertikalnog ubrzanja zabilježeni na Wolong stanici tijekom Wenchuan zemljotresa u Kini, primijenjeni su za pobuđivanje modela. Dobiveni su mnogi podaci, uključujući dinamičke i ukupne pritiske zemlje koji djeluju na stabilizacijski stup, zategnutost užadi i pomake priboja. Usporedbom pritisaka zemljane mase i zategnutosti užadi dobivenih proračunom i ispitivanjima, dobio se koeficijent korelacije od 0,943 i 0,890 za pritisak zemlje, odnosno zategnutosti užadi. To pokazuje da se primjenom predloženog pristupa postigao visoki koeficijent korelacije od gotovo 1,0 između vrijednosti dobivenih ispitivanjem i teorijskih rezultata, pa je dokazano da je predloženi pristup prikladan za praktične primjene.From investigations of damaged earth structures after earthquakes, anchored sheet pile wall has proved to be an excellent seismic structure. However, due to the complexity of the stress system, some fundamental theoretical issues have not been completely solved, so the theoretical development of the structure lags behind application, especially in the development of seismic design theory. In order to make up for this deficiency, a new simplified approach was proposed in this paper, based on previous research. In this approach, the dynamic coupling effect of the pile–soil–anchor was considered, and governing equations were established. In addition, to verify the applicability of the proposed approach, large-scale shaking table tests were performed. In the tests, similitude ratios and similar materials were appropriately applied, and horizontal and vertical acceleration time histories recorded at the Wolong station in the Wenchuan earthquake, China, were used to excite the model. Many time history curves, including dynamic and total earth pressures acting on the stabilizing pile, the cable tensions and the displacements of the wall were obtained. By comparison of the earth pressures and cable tensions between the calculations and tests, the correlation coefficient is 0,943 and 0,890 for earth pressures and cable tensions, respectively. It illustrates that the correlation coefficient between tested values and theoretical results using the proposed theoretical calculation approach is high and close to 1,0, and it is proved that the proposed approach is suitable for practical application

Towards a Digital Twin Framework in Additive Manufacturing: Machine Learning and Bayesian Optimization for Time Series Process Optimization

Laser-directed-energy deposition (DED) offers advantages in additive manufacturing (AM) for creating intricate geometries and material grading. Yet, challenges like material inconsistency and part variability remain, mainly due to its layer-wise fabrication. A key issue is heat accumulation during DED, which affects the material microstructure and properties. While closed-loop control methods for heat management are common in DED research, few integrate real-time monitoring, physics-based modeling, and control in a unified framework. Our work presents a digital twin (DT) framework for real-time predictive control of DED process parameters to meet specific design objectives. We develop a surrogate model using Long Short-Term Memory (LSTM)-based machine learning with Bayesian Inference to predict temperatures in DED parts. This model predicts future temperature states in real time. We also introduce Bayesian Optimization (BO) for Time Series Process Optimization (BOTSPO), based on traditional BO but featuring a unique time series process profile generator with reduced dimensions. BOTSPO dynamically optimizes processes, identifying optimal laser power profiles to attain desired mechanical properties. The established process trajectory guides online optimizations, aiming to enhance performance. This paper outlines the digital twin framework's components, promoting its integration into a comprehensive system for AM.Comment: 12 Pages, 10 Figures, 1 Table, NAMRC Conferenc

pH-sensitive charge-conversion cinnamaldehyde polymeric prodrug micelles for effective targeted chemotherapy of osteosarcoma in vitro

Introduction: Chemotherapy is a common strategy for the treatment of osteosarcoma. However, its therapeutic efficacy is not ideal due to the low targeting, lowbioavailability, and high toxicity of chemotherapy drugs. Nanoparticles can improve the residence time of drugs at tumor sites through targeted delivery. This new technology can reduce the risk to patients and improve survival rates. To achieve this goal, we developed a pHsensitive charge-conversion polymeric micelle [mPEG-b-P(C7-co-CA) micelles] for osteosarcoma-targeted delivery of cinnamaldehyde (CA).Methods: First, an amphiphilic cinnamaldehyde polymeric prodrug [mPEG-b-P(C7-co-CA)] was synthesized through Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT) polymerization and post-modification, and self-assembled into mPEG-b-P(C7-co-CA) micelles in an aqueous solution. The physical properties of mPEG-b-P(C7-co-CA) micelles, such as critical micelle concentration (CMC), size, appearance, and Zeta potential were characterized. The CA release curve of mPEG-b-P(C7-co-CA) micelles at pH 7.4, 6.5 and 4.0 was studied by dialysis method, then the targeting ability of mPEG-b-P(C7-co-CA) micelles to osteosarcoma 143B cells in acidic environment (pH 6.5) was explored by cellular uptakeassay. The antitumor effect of mPEG-b-P(C7-co-CA) micelles on 143B cells in vitro was studied by MTT method, and the level of reactive oxygen species (ROS) in 143B cells after mPEG-b-P(C7-co-CA) micelles treatment was detected. Finally, the effects of mPEG-b-P(C7-co-CA) micelles on the apoptosis of 143B cells were detected by flow cytometry and TUNEL assay.Results: An amphiphilic cinnamaldehyde polymeric prodrug [mPEG-b-P(C7-co-CA)] was successfully synthesized and self-assembled into spheric micelles with a diameter of 227 nm. The CMC value of mPEG-b-P(C7-co-CA) micelles was 25.2 mg/L, and it showed a pH dependent release behavior of CA. mPEG-b-P(C7-co-CA) micelles can achieve chargeconversion from a neutral to a positive charge with decreasing pHs. This charge-conversion property allows mPEG-b-P(C7-co-CA) micelles to achieve 143B cell targeting at pH 6.5. In addition, mPEG-b-P(C7-co-CA) micelles present high antitumor efficacy and intracellular ROS generation at pH 6.5 which can induce 143B cell apoptosis.Discussion: mPEG-b-P(C7-co-CA) micelles can achieve osteosarcoma targeting effectively and enhance the anti-osteosarcoma effect of cinnamaldehyde in vitro. This research provides a promising drug delivery system for clinical application and tumor treatment

Roadmap on signal processing for next generation measurement systems

Signal processing is a fundamental component of almost any sensor-enabled system, with a wide range of applications across different scientific disciplines. Time series data, images, and video sequences comprise representative forms of signals that can be enhanced and analysed for information extraction and quantification. The recent advances in artificial intelligence and machine learning are shifting the research attention towards intelligent, data-driven, signal processing. This roadmap presents a critical overview of the state-of-the-art methods and applications aiming to highlight future challenges and research opportunities towards next generation measurement systems. It covers a broad spectrum of topics ranging from basic to industrial research, organized in concise thematic sections that reflect the trends and the impacts of current and future developments per research field. Furthermore, it offers guidance to researchers and funding agencies in identifying new prospects.AerodynamicsMicrowave Sensing, Signals & System

Poenostavljena metoda za analiziranje nasipov, podprtih s piloti in geosintetsko ojačitvijo, ter analiza vpliva pomembnosti projektnih parametrov

A simplified method for evaluating a pile-supported embankment reinforced with geosynthetic (PGRS embankment) is proposed in this paper. The method takes into account not only the arching effect, the membrane effect of the deflected geosynthetic, and the subsoil reaction, but also the pile head settlement, which makes the method applicable for floating piles, as well as piles seated on a firm soil layer. The settlement of the subsoil surface is considered to consist of two parts: (a) the settlement of the subsoil surface equals that of the pile cap with no deformation in geosynthetic yet(b) the subsoil surface subsides along with the geosynthetic deforming, and the deflected geosynthetic being considered as catenary shaped. The formula for the maximum differential settlement between the subsoil surface and the piles is worked out by analyzing the force equilibrium of the geosynthetic and the stress-strain relationship of the geosynthetic at the edge of the pile cap. The comparison of the calculated results with the observed data and the six current analytical methods has been implemented to verify the proposed method. The influence of the tensile stiffness of the geosynthetic, compression modulus of soft soil, soft soil thickness, embankment height, internal friction angle of the embankment fill and the pile spacing on the subsoil reaction, the stress concentration ratio (SCR) and the tension of the geosynthetic are investigated using the proposed method. The influence significance of these factors has been investigated using the evaluation theory of binary variance analysis for the non-repeatability tests, which helps optimize the design of the PGRS embankment.V tem članku je predlagana poenostavljena metoda za ovrednotenje nasipa, podprtega s piloti in ojačenim z geosintetikom (PGRS nasip). Metoda upošteva poleg ločnega učinka, membranskega učinka odklonjenega geosintetika in reakcije tal, tudi posedek glave pilota. Zaradi slednjega se metoda lahko uporablja tako za viseče pilote kot tudi za pilote, ki stojijo na trdnem zemljinskem sloju. Posedek sloja zemljine pod površjem je sestavljen iz dveh delov: (a) posedka sloja zemljine pod površjem, ki je enak posedku glave pilota brez deformacij v geosintetiku(b) ugrezka sloja zemljine pod površjem zaradi deformiranja geosintetika, pri čemer je upoštevana deformirana oblika za geosintetik enaka obliki deformacije vrvi. Enačba za največji diferencialni posedek med površino podlage in piloti je dobljena s pomočjo analize ravnotežja sil geosintetika in razmerja napetost-specifična deformacija geosintetika na robu glave pilota. Za preveritev predlagane metode je bila izvedena primerjava izračunanih rezultatov z opazovanimi podatki in šestimi trenutnimi analitskimi metodami. Z uporabo predlagane metode je bil preučevan vpliv natezne togosti geosintetika, kompresijskega modula mehke zemljine, debeline mehke zemljine, višine nasipa, notranjega kota trenja nasipnega materiala in razmika pilotov na reakcijo zemljine, razmerja koncentracije napetosti (SCR) in napetosti geosintetika. Učinek teh faktorjev je bil raziskan z uporabo teorije vrednotenja binarne analize variance za neponovljive preizkuse, kar pomaga optimirati načrtovanje PGRS nasipa

Cooperation in Reverse Logistics

Many businesses have now realized that a Reverse Logistics system can be used to gain competitive advantage. Even the best retailers and vendors now have reason to review how their returns programs are managed. New technologies and service providers now offer an opportunity to improve overall ‘total returns performance’. This means not only reducing the ‘total cost of returns’, but utilizing returns to improve customer loyalty, merchandising and product performance. Improving ‘total returns performance’ can transform an increasingly costly and complex process into a competitive advantage. It has forced businesses to reengineer their business processes and look into what can be the next practices in business rather than adopt best practices. Reverse Logistics is a very complex and specialized area of any supply chain and it involves handling individual incoming parcels, opening and inspecting products, communicating with internal departments, customers and vendors and then directing products into disposition channels which will provide the highest value. It is necessary to have a synchronized effort from all the supply chain partners for Reverse Logistics to be successful. This paper explains the various elements of reverse logistics, the need for cooperation in reverse logistics and the opportunities which arise through the processes of Reverse Logistics

Seismic Stability Time-Frequency Analysis Method of Reinforced Retaining Wall

The first-order differential equation of the seismic active earth pressure is established by horizontal slices analysis method, based on the elastic wave theory, with the summarized dynamic analysis model of the reinforced retaining wall and the plane of fracture assumed as linear type. And then this paper proposes a time-frequency analysis method for the internal antiseismic stability analysis on the retaining wall. The reasonability of this method is verified by the results from other methods, for example, rule. The internal frictional angle of filling earth, the seismic intensity, and the frequency of the input earthquake wave have a predominant effect on the needed total tensile force of the lacing wires, which shows that (1) the needed total tensile force of the lacing wires goes up with the increase of the PGA and the internal frictional angle; (2) the needed total tensile force of the expandability lacing wires is bigger than that of the nonexpandability lacing wires; (3) the needed total tensile force of lacing wires is saddle distributed and the force achieves maximum value when the frequency of input wave equals the natural frequency of reinforced retaining wall. Besides, if the reinforced retaining wall is designed in compliance with the rules, the emergency capacity of reinforced retaining wall is reduced. At last, this paper not only takes into account the effect of three factors of the seismic wave (PGA, frequency, and duration) on the internal antiseismic stability analysis of reinforced retaining wall but also provides some valuable references for the time-frequency seismic design of other retaining structures

Spectral analysis of layered sites using shaking table tests.

The dynamic response analysis of horizontal and inclined layered sites using large-scale shaking table tests in various directions, including the dip direction, strike, vertical direction, slope direction and direction perpendicular to the interface of layered sites is conducted in this study. The Fourier spectrum and response spectrum characteristics in the horizontal site are first investigated in this study, and the dynamic responses of the inclined layered sites are then studied and compared to the corresponding responses of the horizontal layered site. The influence of dip angle on the response spectrum is also studied