VeriFi:Towards Verifiable Federated Unlearning

Federated learning (FL) is a collaborative learning paradigm where participants jointly train a powerful model without sharing their private data. One desirable property for FL is the implementation of the right to be forgotten (RTBF), i.e., a leaving participant has the right to request to delete its private data from the global model. However, unlearning itself may not be enough to implement RTBF unless the unlearning effect can be independently verified, an important aspect that has been overlooked in the current literature. In this paper, we prompt the concept of verifiable federated unlearning, and propose VeriFi, a unified framework integrating federated unlearning and verification that allows systematic analysis of the unlearning and quantification of its effect, with different combinations of multiple unlearning and verification methods. In VeriFi, the leaving participant is granted the right to verify (RTV), that is, the participant notifies the server before leaving, then actively verifies the unlearning effect in the next few communication rounds. The unlearning is done at the server side immediately after receiving the leaving notification, while the verification is done locally by the leaving participant via two steps: marking (injecting carefully-designed markers to fingerprint the leaver) and checking (examining the change of the global model's performance on the markers). Based on VeriFi, we conduct the first systematic and large-scale study for verifiable federated unlearning, considering 7 unlearning methods and 5 verification methods. Particularly, we propose a more efficient and FL-friendly unlearning method, and two more effective and robust non-invasive-verification methods. We extensively evaluate VeriFi on 7 datasets and 4 types of deep learning models. Our analysis establishes important empirical understandings for more trustworthy federated unlearning

Ketidaklaziman Kolokasi Pembelajar Bipa dan Implikasinya terhadap Pembelajaran Bahasa

Unacceptable Collocations by Learners of Indonesian as a ForeignLanguage and the Implication in Language Learning. Foreign language learners\u27ability to collocate words that are natural and acceptable in the target language isimportant in foreign language learning; however, it is notoriously difficult forforeign language learners and sometimes makes them frustrated. This studyattempts to describe the negative transfer of English collocations into Indonesiancollocations made by learners of Indonesian as a foreign language in their writingassignments. This study employed a qualitative descriptive method. The data werecollected from 36 writing assignments by 12 learners whose mother tongue isEnglish. They were trainee teachers with experience in teaching Indonesian inAustralia. The finding shows that there are 176 unnatural Indonesian collocations,some of which are negative transfers of learners\u27 mother tongue. This suggests thatdirect teaching of collocations should be given special emphasis in teachingIndonesian as a foreign language

Circular RNA circPVT1 Promotes Proliferation and Invasion Through Sponging miR-125b and Activating E2F2 Signaling in Non-Small Cell Lung Cancer

Background/Aims: Circular RNAs (circRNAs) are key regulators in the development and progression of human cancers, however its role in non-small cell lung cancer (NSCLC) tumorigenesis is not well understood. The aim of this study is to identify the expression level of circPVT1 in NSCLC and further investigated its functional relevance with NSCLC progression both in vitro and in vivo. Methods: Quantative real-time PCR was used for the measurement of circPVT1 in NSCLC specimens and cell lines. Fluorescence in situ hybridization analysis (FISH) assay was used for the identification of sublocation of circPVT1 in NSCLC cells. Bioinformatics analysis, luciferase reporter assay and RNA immunoprecipitation (RIP) were performed to verify the binding of c-Fos at circPVT1 promoter region, and the direct interaction between circPVT1 and miR-125b. Gain- or loss-function assays were performed to evaluate the effects of circPVT1 on cell proliferation and invasion. Western blot and immunohistochemistry assays were performed to detect the protein levels involved in E2F2 pathway. Results: We found that circPVT1 was upregulated in NSCLC specimens and cells. The transcription factor c-Fos binded to the promoter region of circPVT1, resulting in the overexpression of circPVT1 in NSCLC. Knockdown of circPVT1 suppressed NSCLC cell proliferation, migration and invasion, and increased apoptosis. In addition, circPVT1 mediated NSCLC progression via the regulation of E2F2 signaling pathway. More importantly, circPVT1 was predominantly abundant in the cytoplasm of NSCLC cells, and circPVT1 could serve as a competing endogenous RNA to regulate E2F2 expression and tumorigenesis in a miR-125b-dependent manner, which is further verified by using an in vivo xenograft model. Conclusion: circPVT1 promotes NSCLC cell growth and invasion, and may serve as a promising therapeutic target for NSCLC patients. Therefore, silence of circPVT1 could be a future direction to develop a novel treatment strategy

Design of a Compliant Mechanism Based Four-Stage Amplification Piezoelectric-Driven Asymmetric Microgripper

The existing symmetrical microgrippers have larger output displacements compared with the asymmetrical counterparts. However, the two jaws of a symmetrical microgripper are less unlikely to offer the same forces on the two sides of a grasped micro-object due to the manufacture and assembly errors. Therefore, this paper proposes a new asymmetric microgripper to obtain stable output force of the gripper. Compared with symmetrical microgrippers, asymmetrical microgrippers usually have smaller output displacements. In order to increase the output displacement, a compliant mechanism with four stage amplification is employed to design the asymmetric microgripper. Consequently, the proposed asymmetrical microgripper possesses the advantages of both the stable output force of the gripper and large displacement amplification. To begin with, the mechanical model of the microgripper is established in this paper. The relationship between the driving force and the output displacement of the microgripper is then derived, followed by the static characteristics’ analysis of the microgripper. Furthermore, finite element analysis (FEA) of the microgripper is also performed, and the mechanical structure of the microgripper is optimized based on the FEA simulations. Lastly, experimental tests are carried out, with a 5.28% difference from the FEA results and an 8.8% difference from the theoretical results. The results from theoretical calculation, FEA simulations, and experimental tests verify that the displacement amplification ratio and the maximum gripping displacement of the microgripper are up to 31.6 and 632 μm, respectively

A Deep-Convolutional-Neural-Network-Based Semi-Supervised Learning Method for Anomaly Crack Detection

Crack detection plays a pivotal role in structural health monitoring. Deep convolutional neural networks (DCNN) provide a way to achieve image classification efficiently and accurately due to their powerful image processing ability. In this paper, we propose a semi-supervised learning method based on a DCNN to achieve anomaly crack detection. In the proposed method, the training set for the network only requires a small number of normal (non-crack) images but can achieve high detection accuracy. Moreover, the trained model has strong robustness in the condition of uneven illumination and evident crack difference. The proposed method is applied to the images of walls, bridges and pavements, and the results show that the detection accuracy comes up to 99.48%, 92.31% and 97.57%, respectively. In addition, the features of the neural network can be visualized to describe its working principle. This method has great potential in practical engineering applications

Applied Research of NMR Movable Fluid Saturation in Development of Low Permeability Oilfield

In order to improve the production degree of reserves in low permeability oilfield, taking Chang 2 reservoir in Bailangcheng oil region as an example, the movable fluid saturation and its influencing factors were studied by using NMR and high speed centrifugal method, on this basis, the application of movable fluid saturation in low permeability oilfield development is studied. The results show that the pore radius of low permeability reservoir is large, the micro-fine throat is developed, the movable fluid mainly exists in the volume controlled by the throat, the saturation of the movable fluid is low, and the production is difficult. Based on the relationship between the movable fluid saturation and permeability, single well geological reserves and permeability, availability of reserves and remaining movable reserves are evaluated, and the key areas of oilfield development adjustment are determined. According to the movable fluid saturation, the reservoirs are classified to predict the theoretical development effect of the reservoir, and the actual development effect of the oilfield is evaluated by the ratio of the recoverable reserves and movable reserves predicted by the dynamic method, the adjustment space of oil field is analysed. The results of this paper have important reference value for the development policy and adjustment policy of low permeability reservoir

Production evolution patterns and development stage division of waterflooding oilfields

The continuous growth of recoverable reserves in a waterflooding oilfield has a significant impact on the patterns of production evolution. A new production evolution model is established by improving the Weng Cycle model. With the new model, the statistical correspondence between the production decline stage and the reserve-production imbalance is clarified, and the correlation of water cut with the recovery percent of recoverable reserves is discussed, providing quantitative basis of reservoir engineering for dividing development stages of oilfield and defining mature oilfields. According to the statistics of oilfields in eastern China, the time point corresponding to the reserve-production balance coefficient dropping to less than 1 dramatically is well correlated the beginning point of production decline, thus the time when the reserve-production balance coefficient drops dramatically can be taken as the initiation point of production decline stage. The research results show that the water cut and the recovery percent of recoverable reserves have a good statistical match in the high water cut stage, and it is more rational to take both the start point of production decline stage and the water cut of 90% (or the recovery percent of recoverable reserves of 80%) as the critical criteria for defining a mature oilfield. Five production evolution patterns can be summarized as follows: growth—peak plateau—stepped decline, growth—stepped stabilizing—stepped decline, growth—stepped stabilizing—rapid decline, growth—peak plateau—rapid decline, and growth—continuous decline

STUDY ON SAFETY OF T PLATE CONTAINING CRACK BASED ON BS7910

Failure assessment diagram（ FAD） is usually used to evaluate the safety of welded structures containing cracks.There are three assessment levels in BS7910. As the assessment level increases,accuracy is improved and more data is required.This standard is widely used in safety assessment of pressure vessels and pipelines. The working level of offshore crane is relatively high and fatigue cracks can be found on it during the routine inspection. However,due to its high cost and long cycle of maintenance,the productivity is seriously affected. Therefore it is vital to commence safety evaluation on the cracked structure. This paper utilized Shao Yongbo’s experimental data to establish the 3C curves of the cracked structure of offshore crane,and compared it with the 2A curves of the BS7910 standard. The result shows that the tendencies of both curves are the same and 2A curve is more conservative. Thus the structure can be evaluated according to BS7910. This paper offers the critical load of T-plate that contains certain dimension of crack according to level 2A evaluation

Flexural performance of UHPC-filled narrow joints between precast concrete bridge slabs

The deck slabs narrow joints in concrete bridges filled with Ultra-high performance concrete (UHPC) have the potential for wide application and high-efficiency promotion, but there is limited research available on this topic. This paper conducted flexural tests on the new joints. Ten precast concrete deck panels were designed and manufactured for concrete bridges. These panels were connected using UHPC-filled narrow joints. Combined with stress analysis, this study investigates the influence and mechanism of various factors on the mechanical performance of UHPC joints. These factors include the geometric shape of the joint, the roughness of the joint interface, the filling material used in the joint, the width of the joint, and the configuration of joint reinforcement (including the shape and length of lap reinforcement). The test results show that the panel with the UHPC joint filled with steel fibers has excellent flexural and bonding capacity. The jointed panel with a lap length of 140 mm and 120 mm has better flexural performance than the one with a lap length of 90 mm. The straight-jointed panel has a higher flexural capacity compared to the complex triangular-jointed panel. Additionally, reducing the joint width can achieve similar mechanical properties as before. A method has been proposed for calculating the flexural capacity of a jointed panel, utilizing the strut-and-tie model (STM). This method can accurately predict experimental results