Real Metal Research Articles

Copper demand forecasts and predictions of future scarcity

Several studies dealt in the past decades with future predictions of the copper demand, motivated mainly by potential copper shortages that could arise due to insufficient reserves. It is known that there was never a shortage of reserves in order to satisfy demand in the last century and up to the present time. This paper addresses two questions. Did these concerns arise due to excessive demand forecasts, or due to stagnating reserves assumption, or due to both aspects?The article evaluates some of these predictions of future copper demand and compares forecasts with the real metal demand that materialized in past years. Also, it analyses the reserve assumptions of several studies and compares them with what really happened with copper reserves. In the case of recent forecast models that span into future years, whose copper demand is not known yet, a backcasting method was used in order to estimate forecasts, which consists of applying the model in the past.Five out of the seven models rerun in the original periods overestimated demand and two out of them considered that reserves were a fixed stock. Also, the two models studied by the backcasting method considered that reserves were a fixed stock. The four models that considered reserves as a fixed stock run out of reserves, irrespective of whether they overestimated or underestimated demand. These results suggest that predictions of a future scarcity of copper could be mainly attributed to the assumption of a fixed stock of reserves and not necessarily to overestimations of demand. The remaining five models did not consider the future availability of copper.

The Relationship Between China’s Real Estate Market and Industrial Metals Futures Market: Evidence from Non-price Measures of the Real Estate Market

By using non-price indicators of the real estate market, this paper examines the relationship between the real estate market and the industrial metals futures market in China during the 2004–2019 period. Empirical findings from a vector autoregression model (VAR), a causality study, and cointegration analysis suggest that, in the context of China, industrial metals futures have both short-run and long-run associations with the real estate market. The effectiveness of the mechanisms through which the real estate market affects the industrial metals futures market, however, varies across underlying assets and pre-specified indicators. More specifically, the shock of the size of newly started constructions has the greatest accumulated impacts on the copper futures market, increasing the price of copper futures by 2.46% after two years. Additionally, 11.31% of the changes in the price of copper futures can be attributed to fluctuations in the size of newly started constructions, in which the explanatory power has increased horizontally. The results of impulse response functions (IRFs) show that the price of rebar futures is the most sensitive to volatility in sales size in the real estate market, in which the rebar futures price can be expected to increase by 1.65% after two years. The results of the forecast error variance decomposition (FEVD) method suggest that fixed asset investment in the real estate market makes the largest contribution (about 6.28%) to corresponding movements in the rebar futures price.

Electron Transfer through a Natural Oxide Layer on Real Metal Surfaces Occurring during Sliding with Polytetrafluoroethylene: Dependence on Heat of Formation of Metal Oxides

Electron emission (EE) from real metal surfaces occurring during sliding contact with a polytetrafluoroethylene (PTFE) rider has been investigated using the thermodynamic data of metal oxides and the X-ray photoelectron spectroscopy (XPS) intensity ratio of oxygen/metal on the surfaces. EE was termed triboelectron emission (TriboEE). Rolled metal sheets of 18 types were used. The metal‒oxygen bond energy calculated from the heat of the formation of metal oxide, (D(M–O)), was shown to be a key factor in dividing the EE into two routes, the so-called Schottky effect and the tunnel effect, due to the surface oxide layer. The metals in periodic groups 4 (Ti and Zr), 5 (V, Nb, and Ta), and 6 (Mo and W) maintained higher values of D(M–O), while, moving down the groups, the TriboEE intensity increased, being ascribed to the former route. In groups 10 (Ni, Pd, and Pt) and 11 (Cu, Ag, and Au), the D(M–O) values decreased moving down the groups, but the TriboEE intensity increased significantly, which can be attributed to the latter route. Furthermore, with the increase in the electrical conductivity of metals, the TriboEE intensity became remarkably high, while the D(M–O) value fell rapidly and became almost constant. The XPS results showed that the dependence of the D(M–O) and XPS metal core intensity on the O1s intensity and the XPS intensity ratio of the O1s/metal core was different between groups 10 and 11 and groups 4, 5, and 6. It was concluded that, under the electric field caused on the real metal surface by the friction with PTFE, the electron from metals with small D(M–O) values predominantly tunnels the surface oxide layer as a surface barrier, while with large D(M–O) values, the electron passes over the top of the barrier.

Engineering of amine-based binding chemistry on functionalized graphene oxide/alginate hybrids for simultaneous and efficient removal of trace heavy metals: Towards drinking water

Engineering of versatile binding chemistry on graphene oxide surface using nucleophilic substitution/amidation reactions for highly efficient adsorption of Cd (II), Cu (II) and Pb (II) is herein proposed. Graphene oxide (GO) was used as a precursor for covalent bonding of hexamethylenediamine (HMDA) molecules via the nucleophilic substitution/amidation reactions on epoxy (COC) and carboxyl (COOH) groups to yield hexamethylenediamine functionalized graphene oxide (GO-HMDA) with multiple binding chemistries such as oxygen and nitrogen. Afterwards, GO-HMDA was encapsulated in alginate hydrogel beads with different loadings 5, 10, 15 and 20 wt% to produce Alg/GO-HMDA hybrid adsorbents for the removal of trace heavy metal ions from aqueous solution. Batch adsorption studies showed remarkable adsorption rates reaching 100% for Pb (II), 98.18% for Cu (II) and 95.19 for Cd (II) (~1 mg L−1) with only 15 wt% of GO-HMDA incorporated into the alginate beads. Moreover, Alg/GO-HMDA showed high removal efficiencies of heavy metals from tap water with a removal order of (Pb > Cu > Cd) similar to that observed in single aqueous solution. In Addition, the Alg/GO-HMDA adsorbents displayed excellent regeneration ability for six consecutive adsorption–desorption cycles confirming the high performance and potential of these adsorbents, for real heavy metals remediation in environment and in drinking waters in both single and multiple systems. Finally, the adsorption mechanism of traces heavy metals resulted from several phenomena including the electrostatic interactions occurring between the COOH groups of Alginate and the GO-HMDA surface groups as well as, through chelation interactions occurring between the metal cations and amino-functionalized groups of Alg/GO-HMDA 15 hybrid adsorbent.

Regularization-based Continual Learning for Anomaly Detection in Discrete Manufacturing

The early and robust detection of anomalies occurring in discrete manufacturing processes allows operators to prevent harm, e.g. defects in production machinery or products. While current approaches for data-driven anomaly detection provide good results on the exact processes they were trained on, they often lack the ability to flexibly adapt to changes, e.g. in products. Continual learning promises such flexibility, allowing for an automatic adaption of previously learnt knowledge to new tasks. Therefore, this article discusses different continual learning approaches from the group of regularization strategies, which are implemented, evaluated, and compared based on a real industrial metal forming dataset.

The impact of macroeconomic and oil shocks on India’s non-ferrous metal prices: A structural-VAR approach

This paper compares the value shocks from the real interest rates, real exchange rates, real crude prices, and other key macroeconomic variables on the metal prices. The structural VAR models are estimated on monthly data over the period 2005m12–2019m12 to determine the asymmetric effect of the macroeconomic shocks and determine whether commodity prices display overshooting behavior in response to these shocks. The impulse response and the forecast error variance decomposition function analyze the short-term impacts on the Indian non-ferrous metal prices. The results indicate that the metals index, and crude oil have a significant positive impact on the prices of metals, while the real interest rate negatively affects India’s metal prices. The impact of the real exchange rate and own shocks on real metal prices is found to be insignificant. Metal prices tend to display an overshooting behavior in response to changes in the real interest rate. Besides, the forecast error variance decomposition reveals the incremental contribution of crude oil prices in explaining the behaviour of metal prices.

ЕЛЕКТРОМАГНІТНІ ПРОЦЕСИ В СИСТЕМІ З ПЛОСКИМ КРУГОВИМ СОЛЕНОЇДОМ МІЖ МАСИВНИМИ БІФІЛЯРНИМИ КОТУШКАМИ

Purpose. Currently, in order to save materials and energy costs, devices have been developed using inductor systems with bifilar coils used in equipment for magnetic-pulse processing of metals. The purpose of this work is to obtain design relations based on a rigorous solution of the edge electrodynamics for the analysis of electromagnetic processes in a real metal of a circular solenoid of finite thickness placed between massive multi-turn coils of a bifilar with unidirectional currents in a flat inductor system. Methodology. To solve this problem, Maxwell’s equations with appropriate boundary conditions and Laplace transforms were used. Results. Based on the exact solution of the boundary value problem, the space-time function of the density of the induced current, which arises in a flat solenoid when the system is excited by harmonic unidirectional currents in massive bifilar windings, is obtained. On the basis of numerical calculations, it was found that in the low-frequency mode, the transverse distribution of the induced current is linear, symmetric about the central axis of the inductor. In the high-frequency mode, the transverse distribution of the induced current is characteristic of the case of a sharp surface effect. The conditions for the minimum influence of the fields of the external bifilar on the processes in the internal inductor are revealed. Originality. The novelty of this work lies in proposing the idea of the design of the inductor system, as well as in the exact solution of the electrodynamics problem and obtaining the calculated expressions for the analysis of electromagnetic processes. Practical value. On the basis of the obtained formulas and the performed calculations, the efficiency of the proposed calculation model has been proved, which makes it possible to use it as a basic model for similar inductor systems in determining the real conditions of their maximum efficiency. Figures 2, references 17.

Mechanisms of construction machines and selection of steels for the manufacture of welded metal structures

The paper is devoted to the study of the working mechanisms of construction machines from the point of view of the selection of structural steels for the manufacture of welded metal structures. Special attention is paid to the operational reliability and durability of modern construction machines. It was found that the most suitable for the manufacture of welded structures are complex-alloyed low-carbon steels. They have high strength (σ0.2≥600 MPa, σB≥800 MPa), are characterized by sufficient plasticity and increased resistance to brittle fracture at low temperatures. In the selection process, special attention was paid to the properties that structural steels should simultaneously have, specifically: low sensitivity to various stress concentrators; adaptability to perform service functions that are envisaged in the development of the project and directly in the process of manufacturing the welded metal structure, good weldability. The experiments were carried out using the example of low-carbon and low-alloy steels. Special attention was paid to the analysis of the optimal modes of thermal cycling with the aim of obtaining final structures with a given degree of dispersion, typical of real metal structures. Taking into account the requirements for the reliability of construction machines in operating conditions at high and low temperatures, as well as taking into account various operational characteristics, the expediency of using ferromagnetic structural steels was substantiated.

Kinematics of the shaped charge jet formation process

Based on the review of scientific and technical literature, an analysis is made of the problems of the modern theory of formation, extension and destruction of the shaped jet. The focus of the research is on the kinematics of the formation of a shaped jet based on the approach of operating with the characteristics of a real metal when the velocity vector of the cumulative jet is the result of three vectors: strain, strain and displacement of the shaped jet’s material. The numerical experiment of the functioning of the shaped charge is carried out, and the procedure for evaluating the calculation results is proposed. The obtained data correlate with existing knowledge about the physics of the cumulation process.

Exciton oscillator strength in two-dimensional Dirac materials

Exciton problem is solved in the two-dimensional Dirac model with allowance for strong electron-hole attraction. The exciton binding energy is assumed smaller than but comparable to the band gap. The exciton wavefunction is found in the momentum space as a superposition of all four two-particle states including electron and hole states with both positive and negative energies. The matrix element of exciton generation is shown to depend on the additional components of the exciton wavefunction. Both the Coulomb and the Rytova-Keldysh potentials are considered. The dependence of the binding energy on the coupling constant is analyzed for the ground and first excited exciton states. The binding energy and the oscillator strength are studied as functions of the environmental-dependent dielectric constant for real transition metal dichalcogenide monolayers. We demonstrate that the multicomponent nature of the exciton wavefunction is crucial for description of resonant optical properties of two-dimensional Dirac systems.

Microwave Magnon-Plasmon-Polaritons in the Ferromagnetic Metal–Screened Insulator Structure

A possibility for surface magnon–plasmon–polaritons (SMPPs)–coupled microwave oscillations of magnetization, electron density, and electromagnetic field–to exist in real ferromagnetic metal–insulator–ideal non-magnetic metal structures has been analyzed theoretically. The developed theory predicts that the effective formation of SMPPs is possible only at certain values of the external dc magnetic field and must be accompanied by a shift in the characteristic frequency of the resonance plasmon-polariton systems. A theoretical estimation of the frequency shift for SMPPs in the structure “surface electromagnetic wave resonator made of permalloy–vacuum–ideal metal” gives a value of ±45 MHz for a resonator with a characteristic frequency of 10 GHz, which seems sufficient for this effect to be observed experimentally.

Computational screening of metal–organic framework structures for separation of propane/propene mixture

ABSTRACT In this article, we present a high-throughput computational screening of real metal–organic framework (MOF) structures to identify the best candidate material for the separation of propane/propene mixture. We assessed the performances of the MOFs by calculating various metrics such as adsorption selectivity, working capacity, regenerability and adsorbent performance score (APS). All most all of these MOFs are selective to propane over propene. We looked at various structures–property correlations that revealed some useful insights and ways of tuning the structural properties of the MOFs to yield high performance. The MOFs were ranked on the basis of APS. MOF RUFPUF was found to be the best performing MOF with a highest APS value of mol/kg and . We also screened out few potential stable MOFs containing tetravalent metal cations such as Zr4+, HF4+ and Ti4+. MOF BOLZIN (NU-1100) was found to be the best performing stable MOF with APS mol/kg and .

Generalized thermoelastic effect in real metals and its application for describing photoacoustic experiments with Al membranes

A generalized theoretical model of the formation of a thermoelastic photoacoustic signal from real materials is proposed taking into account the presence of defects and impurities. An effective coefficient of thermal expansion was introduced that describes the dilatation effect of thermally activated lattice irregularities. Expressions for the thermoelastic photoacoustic signal obtained in the linear approximation were applied to describe aluminum membrane vibrations at the periodic laser excitation measured in other studies using a gas-microphone open-cell photoacoustic technique. The proposed theoretical model allows us to explain the experimental results in the 20 Hz–7 kHz modulation frequency range without invoking the assumption of the bulk absorption of pump laser radiation in aluminum membranes.

Visual simulation of weathering coated metallic objects

Weathering, referring to techniques for depicting outdoor objects as having suffered rain and wind damage, has a long history of research, and many methods can be found in the literature. Metal is a representative target of weathering, as metallic surface corrosion is a widespread deterioration phenomenon in our daily life. However, few weathering methods consider the effects of rust-preventive paint, while real metal is usually treated with a preservative. This paper presents a novel procedural method for weathering coated metal objects. In our method, a coated surface is imposed on a 3D triangular mesh. We enable the mechanical deterioration of coating film, and we deform the mesh model to express cracking and peeling. As further defacing elements on the coating film, runoff rust and darkening are reproduced by changing the color and reflectance of the surface. Besides, by locally adjusting the control parameters of the designated areas on the surface, the process of deterioration can be arbitrarily directed. Several visual simulation results are shown to prove empirically the faithfulness of the proposed methods.

Generalized circuit model for analysis of extraordinary transmission in multilevel slits.

We propose a generalized circuit model for accurate analysis of the extraordinary transmission phenomenon in multilevel stepped slit structures. The multilevel stepped slit consists of some continuous sub-wavelength metal slits with different widths. By applying the proposed circuit model, we study the extraordinary transmission property of this structure for the two cases of ideal and real metal structures. The accuracy of the achieved results is validated by a full wave analysis based on the finite element method. Additionally, since the multilevel slit structure is adjustable by simply manipulating slit parameters such as widths and heights, various kinds of transmission spectra and a different number of resonance points are investigated by the circuit model and the numerical approach. Multilevel stepped slits can be used potentially as bandpass filters or optical attenuators in photonics integrated circuits.

Removal of As(V), Cr(VI) and Cu(II) using novel amine functionalized composite nanofiltration membranes fabricated on ceramic tubular substrate

Novel amine functionalized composite membranes were prepared over tubular ceramic substrate using facile dip-coating and cross-flow filtration approach. The two fabricated membranes, P-60S and P-60S-EDTA with polyethyleneimine (PEI) and EDTA-modified PEI as functional layers respectively, were characterized in terms of EDX, FTIR, XPS, FESEM, AFM and contact angle analyses which confirmed their stable physical and chemical structure for use in high pressure application. Clean water permeability and MWCO study revealed the superior permeability and rejection efficiency of the P-60S-EDTA compared to the P-60S membrane. Incorporation of bulky EDTA molecules in the membrane functional layer simultaneously decreased pore size and increased membrane hydrophilicity. The removal of As(V), Cr(VI) and Cu(II) heavy metals by both membranes were found to be highly pH dependent and overall rejection improved in case of P-60S-EDTA membrane [99.82% for Cu(II), 96.75% for As(V) and 97.22% for Cr(VI)]. Interestingly, rejection of As(V) and Cr(VI) was significantly improved in presence of Cu(II) due to volume resistance provided by EDTA-Cu(II) complex towards the passage of other heavy metal ions. Excellent stability of P-60S-EDTA membrane in continuous operation of 36 h in both ideal and practical water environment suggests its promising application in real field heavy metal contaminated waste water treatment.

Long-term prediction of the metals’ prices using non-Gaussian time-inhomogeneous stochastic process

Stochastic models traditionally used to describe metals’ prices have proved not to be suitable to represent the dynamic behavior and time-related nature of metal markets. Rates of return are characterized by non-Gaussian and heterogeneous characteristics, which requires the use of properly adjusted models. In this paper, we introduce a stochastic model that takes under consideration the mentioned specific characteristics of the real data corresponding to the mineral commodity prices, namely the non-homogeneous character (time-dependent characteristics) and non-Gaussian distribution. The introduced model is in some sense the extension of the classical Ornstein–Uhlenbeck process (called also the Vasicek model) which was originally used to the interest rate data description. The proposed in this paper model, in contrast to the classical process, has the time-dependent parameters. This perfectly captures the time-dependent characteristics of the real data. Moreover, it is based on the general class of the skewed Student’s t-distribution (SGT), which is related to the non-Gaussian behavior of the real metals’ prices. This paper is a continuation of the authors’ previous research where the simpler model (Chan–Karolyi–Longstaff–Sander, CKLS) based on the SGT distribution was proposed. We demonstrate here the step-by-step procedure of the time-dependent parameters’ estimation and check its effectiveness by using the simulated data. Finally, based on the real-time series analysis, we demonstrate that the proposed stochastic model is universal and can be applied to metals’ prices description for the long-term prediction.

Metal prices made in China? A network analysis of industrial metal futures

AbstractIn addition to being the world's greatest consumer and producer of industrial metals, China now also features the most actively traded industrial metal futures contracts worldwide. To examine China's role in the global price formation process of industrial metal futures markets, we use a sample of 29 futures contracts traded on exchanges in the United States, the United Kingdom, India, and China. We estimate vector autoregressive models and conduct variance decompositions, which are then visualized in the form of networks. The results indicate that China, despite its role as key actor in both real and financial industrial metal markets, is a price taker.

Influences of electronic spin structures on the magnetic properties of Fe, Co and Ni ions and the adsorption of collectors

The electronic spin properties of Fe, Co and Ni metal ions in the octahedral field formed by S and O ligands were studied by density functional theory (DFT). It is found that in MO octahedral field, the metal exhibits a high spin nature, whereas in MS octahedral field, the metal exhibits a low spin nature. This suggests that O atom is a weak-field ligand and S atom is a strong-field ligand. It is found that MO atoms are mainly ionicly bonded, whereas MS atoms are mainly covalently bonded. This result is consistent with the MO and MS bonds in the real metal oxide and sulfide minerals. Hence, MO and MS coordination compound models can be used to simulate the crystals of the real oxide and sulfide minerals. Then the adsorption of O- and S-containing flotation collectors on these two mineral models was studied. It is indicated that S-containing collectors could not effectively collect oxide minerals, but O-containing collectors have strong collecting ability to oxide minerals. In addition, the collecting ability of S- and O-containing collectors to sulfide minerals is nearly the same. These are consistent with the flotation practice that O-containing collectors have no selective collecting capacity on oxide and sulfide minerals but S-containing collectors have strongly selectively collecting capacity to sulfide minerals.

Beyond Digital Domain: Fooling Deep Learning Based Recognition System in Physical World

Adversarial examples that can fool deep neural network (DNN) models in computer vision present a growing threat. The current methods of launching adversarial attacks concentrate on attacking image classifiers by adding noise to digital inputs. The problem of attacking object detection models and adversarial attacks in physical world are rarely touched. Some prior works are proposed to launch physical adversarial attack against object detection models, but limited by certain aspects. In this paper, we propose a novel physical adversarial attack targeting object detection models. Instead of simply printing images, we manufacture real metal objects that could achieve the adversarial effect. In both indoor and outdoor experiments we show our physical adversarial objects can fool widely applied object detection models including SSD, YOLO and Faster R-CNN in various environments. We also test our attack in a variety of commercial platforms for object detection and demonstrate that our attack is still valid on these platforms. Consider the potential defense mechanisms our adversarial objects may encounter, we conduct a series of experiments to evaluate the effect of existing defense methods on our physical attack.