The effect of electromagnetic stirring on the enrichment of primary silicon from Al–Si melt during the process of electromagnetic separation was investigated. It is shown that the enrichment of ...primary silicon in Al–Si melt strongly depends on the melt flowing and viscosity gradient. The efficient enrichment of primary silicon was achieved by implementing a high current intensity, which induced a high intense melt flowing. Also, the remaining primary Si in Al–Si alloy could be precipitated by gradually decreasing the current intensity. Additionally, the inductively coupled plasma mass spectrometry (ICP-MS) results show that Si purification is attributed with the enrichment of primary silicon. In this work, the impurity content in primary silicon is 43.3ppmw, which is much smaller than 777.6ppmw in metallurgical silicon. Therefore, a potential low-cost technology would be provided for the Si purification.
•The efficient separation of primary Si crystals and Al–Si alloy has been achieved.•The impurity content of Si has been decreased from 777.6ppmw to 43.3ppmw.•The effect of electromagnetic stirring on the enrichment of Si was discussed.
Tropopause fold is the primary mechanism for stratosphere-troposphere exchange (STE) at the midlatitudes. Investigation of the features of tropopause folds over the Tibetan Plateau (TP) is important ...since the TP is a hotspot in global STE. In this study, we investigated seasonal features of the tropopause fold events over the TP using the 40-year ERA-Interim reanalysis data. The development of a tropopause folding case is specifically examined. The results show that shallow tropopause folds occur mostly in spring, while medium and deep folds occur mostly in winter. The multiyear mean monthly frequency of shallow tropopause folds over the TP reaches its maximum value of about 7% in May and then decreases gradually to its minimum value of 1% in August and increases again since September. Deep folds rarely occur in summer and autumn. Both the seasonal cycle and seasonal distribution of total tropopause folds over the TP are dominated by shallow folds. The relative high-frequency areas of medium and deep folds are located over the southern edge of the TP. The westerly jet movement controls the displacement of the high-frequency folding region over the TP. The region of high-frequency tropopause folds is located in the southern portion of the plateau in spring and moves northward in summer. The jet migrates back to the south in autumn and is located along about 30°N in winter, and the region where folds occur most frequently also shifts southward correspondingly. A medium fold event that occurred on 29 December 2018 is used to demonstrate the evolution of a tropopause fold case over the TP in winter; that is, the folding structure moves from west to east, the tropopause pressure is greater than 320 hPa over the folding region, while it is about 200 hPa in the surrounding areas, and the stratospheric air with high potential vorticity (PV) is transported from the high latitudes to the plateau by meridional winds. A trajectory model result verifies the transport pathway of the air parcels during the intrusion event.
In this paper, we present invalid-curve attacks that apply to the hyperelliptic curve scalar multi- plication （HECSM） algorithm proposed by Avanzi et al. on the genus 2 hyperelliptic curve over ...binary field. We observe some new properties of the HECSM. Our attacks are based on these new properties and the obser- vation that the parameters f0 and fl of the hyperelliptic curve equation are not utilized for the HECSM. We show that with different ＂values＂ for curve parameters f0, fl, there exsit cryptographically weak groups in the Koblitz hyperelliptic curve. Also, we compute the theoretical probability of getting a weak Jacobian group of hyperelliptic curve whose cardinality is an smooth integer.
In STOC 2008, Peikert and Waters introduced a powerful primitive called lossy trapdoor functions (LTFs). In a nutshell, LTFs are functions that behave in one of two modes. In the normal mode, ...functions are injective and invertible with a trapdoor. In the lossy mode, functions statistically lose information about their inputs. Moreover, the two modes are computationally indistinguishable. In this work, we put forward a relaxation of LTFs, namely, regular lossy functions (RLFs). Compared to LTFs, the functions in the normal mode are not required to be efficiently invertible or even unnecessary to be injective. Instead, they could also be lossy, but in a regular manner. We also put forward richer abstractions of RLFs, namely all-but-one regular lossy functions (ABO-RLFs) and one-time regular lossy filters (OT-RLFs).
We show that (ABO)-RLFs admit efficient constructions from both a variety of number-theoretic assumptions and hash proof system (HPS) for subset membership problems satisfying natural algebraic properties. Thanks to the relaxations on functionality, the constructions enjoy much compact key size and better computational efficiency than that of (ABO)-LTFs.
We demonstrate the utility of RLFs and their extensions in the leakage-resilient cryptography.•As a special case of RLFs, lossy functions imply leakage-resilient injective one-way functions with optimal leakage rate 1−o(1).•ABO-RLFs (or OT-RLFs) immediately imply leakage-resilient one-time message authentication code (MAC) with optimal leakage rate 1−o(1).•ABO-RLFs together with HPS give rise to leakage-resilient chosen-ciphertext (CCA) secure key encapsulation mechanisms (KEM) (this approach extends naturally to the identity-based setting). Combining the construction of ABO-RLFs from HPS, this gives the first leakage-resilient CCA-secure public-key encryption (PKE) with optimal leakage rate based solely on HPS, and thus goes beyond the barrier posed by Dodis et al. (Asiacrypt 2010). Our construction also applies to the identity-based setting, yielding LR-CCA secure IB-KEM with higher leakage rate than previous works.
•Six carboxylic ionic liquids were synthesized to selectively separate Al3+/Gd3+.•High Al3+/Gd3+ separation factor of 923 was achieved by N1888C7H11O2 for industrial GdCl3 feed.•High Al3+ removal ...rate of 98.69% was obtained within one-step extraction.•Loaded N1888C7H11O2 can be efficiently regenerated by 0.6 mol‧L−1 HCl solution and 0.5 mol‧L−1 NaOH solution.•The extraction efficiency of Al3+ with regenerated N1888C7H11O2 was only reduced by 3% after five cycles.
As the associated element of ion-adsorbed type rare earth ores, aluminum ion (Al3+) has a great influence on the purification of gadolinium ion (Gd3+). In this paper, six carboxylic ionic liquids were synthesized with methyltrioctylammonium (N1888+) as cation and carboxyl group as anion, and optimized for selective separation of Al3+/Gd3+. The extraction capability, separation factor, stripping property and recycling stability of the ionic liquid on the separation of Al3+ and Gd3+ were systematically investigated. In addition, the loaded Al3+ can be totally stripped by 0.08 mol‧L−1 HCl solution. A particularly high separation factor of 923 can be obtained for removing Al3+ from industrial GdCl3 feed solution (762 mg‧L−1 Al3+ and 146 g‧L−1 Gd3+). The removal rate of Al3+ was up to 98.69% and the recovery rate of Gd3+ achieved at 92.47% by carboxylic ionic liquid (N1888C7H11O2) in one-step extraction. After 0.6 mol‧L−1 HCl solution stripping and 0.5 mol‧L−1 NaOH solution regenerating, the extraction efficiency of Al3+ was only reduced by 3% after 5 cycles of organic phase. With the low acid and base concentration, it greatly reduced the chemical consumption and significantly the emission of high ammonia–nitrogen wastewater inindustry. This work provides a low-carbon process for efficient removal of Al3+ from industrial GdCl3 feed by carboxylic ionic liquids.
In cryptography and algorithmic number theory, modular inversion is viewed as one of the most common and time-consuming operations. It is hard to be directly accomplished on resource-constrained ...clients (e.g., mobile devices and IC cards) since modular inversion involves a great amount of operations on large numbers in practice. To address the above problem, this paper proposes a novel unimodular matrix transformation technique to realize secure outsourcing of modular inversion. This technique makes our algorithm achieve several amazing properties. First, to the best of our knowledge, it is the first secure outsourcing computation algorithm that supports arbitrary and variable modulus, which eliminates the restriction in previous work that the protected modulus has to be a fixed composite number. Second, our algorithm is based on the single untrusted program model, which avoids the non-collusion assumption between multiple servers. Third, for each given instance of modular inversion, it only needs one round interaction between the client and the cloud server, and enables the client to verify the correctness of the results returned from the cloud server with the (optimal) probability 1. Furthermore, we propose an extended secure outsourcing algorithm that can solve modular inversion in multi-variable case. Theoretical analysis and experimental results show that our proposed algorithms achieve remarkable local-client's computational savings. At last, as two important and helpful applications of our algorithms, the outsourced implementations of the key generation of RSA algorithm and the Chinese Reminder Theorem are given.
Aluminum (Al) is often associated with rare earth resources, and the removal of Al3+ from rare earth elements (REEs) is a difficult task due to its amphoteric properties. Aluminum ions (Al3+) enrich ...in Sm3+-Gd3+ solution with the traditional 2-Ethylhexylphosphoric acid mono-2-ethylhexyl ester (P507)-kerosene-HCl system, emulsifying the phases, polluting the rare earth products and reducing the separation efficiency. A readily industrialized ionic liquid (IL) was synthesized with methyltrioctylammonium chloride (N1888Cl) and industrial naphthenic acid (NA) for the purification of Al3+ from GdCl3 solution. Under the experimental conditions, the extraction properties of diluted N1888NA, diluted NA and saponified NA were comparatively investigated and the separation factors (βAl/Gd) of Al/Gd were 23.0, 3.5 and 1.3, respectively. The effects of the salting-out agent, extraction agent, pH value and phase ratio on metal extraction efficiency were optimized. Finally, the industrial GdCl3 feed with a high Al3+ impurity of 889 mg/L was lowered to 5 mg/L. The removal efficiency of Al3+ was 99.4%, and the purity of Gd3+ was 99.998%. It provides a potential method for Al3+ purification from rare earth solutions with advantages of high efficiency, raw materials availability and ready industrialization.
A readily industrialized ionic liquid was synthesized from N1888Cl and NA, the two common, cheap and available precursors, for the purification of Al3+ from industrial GdCl3 leach liquor. High Al3+ impurity of 889 mg/L can be lowered to 5 mg/L within three steps. The removal efficiency of Al3+ was 99.4%, and the purity of Gd3+ was 99.998%. The ionic liquid based on available raw materials provides an extractant for rare earth purification with high efficiency. Display omitted
•A readily industrialized ionic liquid was synthesized for rare earth purification with high efficiency.•The separation factor of Al3+ and Gd3+ (βAl/Gd) was as high as 23.•High Al3+ impurity of 889 mg/L in industrial solutions can be lowered to 5 mg/L within three steps.•The extraction efficiency of Al3+ was only reduced by 3.5% with the ionic liquid system after 5 times of regeneration.•The removal efficiency of Al3+ was 99.4%, and the purity of Gd3+ was 99.998%.
A Verifiably Encrypted Signature (VES) scheme encrypts a digital signature in a way that allows the public to verify the validity of the encrypted signature. Recently, several practical VES schemes ...for ECDSA have been proposed to enable escrowed transactions with cryptocurrencies. However, these schemes are inefficient in terms of both communication and computation, or require a large lookup table. In this paper, we present two efficient VES schemes for ECDSA that improve upon previous work. The first scheme is based on Castagnos-Laguillaumie (CL) encryption, while the second is based on modified Joye-Libert (JL) encryption. Our benchmark shows that our schemes outperform existing constructions by a factor of at least 2 in both computation and communication. Additionally, our solution does not rely on any lookup table. We demonstrate that these schemes can also be generalized to design VES for Schnorr signature scheme and EdDSA. The main technical contribution of this paper, which is of independent interest, is a zero-knowledge proof for the equality of the discrete log of an elliptic-curve point and that of a JL ciphertext. Importantly, the security of our proof does not rely on any non-standard assumptions.
Solar grade silicon (SOG-Si) and hypereutectic Al-Si alloys with low silicon (silicon composition below 25 pct) can be successfully obtained by separation of hypereutectic Al-Si alloy with high ...silicon (silicon composition above 30 pct) under an alternating electromagnetic field after post-processing. To explore the separation mechanism in detail, experiments were conducted in this study using a high-frequency induction furnace with different pulling conditions of the crucible which is loaded with Al-45 wt pct Si melt. Results demonstrate that the separation of hypereutectic Al-Si alloy is feasible through either a pull-up or drop-down process. The height of each separation interface between the compact and sparse parts of the primary silicon decrease as the pull-up distance rose. When the pulling rate is very low, resultant morphologies of compact primary silicon are rounded and polygonal, allowing for more effective separation of the primary silicon. A novel physical model is presented here based on the experimental results and simulation. The model can be used to effectively describe the separation mechanism of primary silicon from hypereutectic Al-Si melts under alternating electromagnetic fields.
Private Set Intersection (PSI) protocols can securely compute the intersection of the private sets on the server and the client without revealing additional data. This work introduces the concept of ...Privacy-Preserving Feature Retrieved Private Set Intersection (<inline-formula> <tex-math notation="LaTeX">\mathsf {P^{2}FRPSI} </tex-math></inline-formula>). In <inline-formula> <tex-math notation="LaTeX">\mathsf {P^{2}FRPSI} </tex-math></inline-formula> protocols, the client can obtain the intersection that satisfies a given predicate without revealing the predicate and additional data. We formally define the <inline-formula> <tex-math notation="LaTeX">\mathsf {P^{2}FRPSI} </tex-math></inline-formula> protocol, including its inputs, outputs, functionality, and security. To achieve the privacy guarantee in <inline-formula> <tex-math notation="LaTeX">\mathsf {P^{2}FRPSI} </tex-math></inline-formula> protocols, a new two-party protocol is designed, namely Secure Secret Shared Retrieval (<inline-formula> <tex-math notation="LaTeX">\mathsf {S^{3}R} </tex-math></inline-formula>), which can be used to securely determine whether each item on the server satisfies the predicate. We construct an <inline-formula> <tex-math notation="LaTeX">\mathsf {S^{3}R} </tex-math></inline-formula> protocol and prove its security in the semi-honest model. On the basis of this, we design an efficient OT-based <inline-formula> <tex-math notation="LaTeX">\mathsf {P^{2}FRPSI} </tex-math></inline-formula> protocol and an easy-to-implement DH-based <inline-formula> <tex-math notation="LaTeX">\mathsf {P^{2}FRPSI} </tex-math></inline-formula> protocol and prove that they are secure in the semi-honest model. Our implementation shows that the OT-based <inline-formula> <tex-math notation="LaTeX">\mathsf {P^{2}FRPSI} </tex-math></inline-formula> protocol can perform the matching for about 1000K items in 3.8 seconds with a single thread. Moreover, the DH-based <inline-formula> <tex-math notation="LaTeX">\mathsf {P^{2}FRPSI} </tex-math></inline-formula> can perform the matching for about 7000K items in one hour with four threads, with communication totaling 1456 MB, while the OT-based <inline-formula> <tex-math notation="LaTeX">\mathsf {P^{2}FRPSI} </tex-math></inline-formula> protocol requires 1673 MB.
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