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1. A Bandstop Filter Based on an Optimum Bandstop Filter

   Yang, Shujun; Nyarko, Kofi (April 2021, International journal of advanced research in electrical electronics and instrumentation engineering)

   null (Ed.)

   A microstrip bandstop filter (BSF) based on an optimum BSF is presented. The original BSF has three open stubs. One narrow stub is attached onto the left open stub, and the length of the right open stub is reduced to form the new BSF. The filter is simulated on Sonnet Lite software. Simulation results show the new filter generates a wider stopband without increasing the circuit size. 

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2. WE-Filter: Adaptive Acceptance Criteria for Filter-based Shared Autonomy

   https://doi.org/10.1109/ICRA48891.2023.10161228  

   Bowman, Michael; Zhang, Xiaoli (May 2023, IEEE International Conference on Robotics and Automation)
3. Coherent light filter

   https://doi.org/10.1364/OL.447393  

   Bergthold, Morgan; Stewart_Jr, Keith; Duggar, Nicholas; Muhowski, Aaron_J; Wasserman, Daniel (May 2022, Optics Letters)

   We demonstrate efficient filtering of coherent light from a broad spectral background. A Michelson interferometer is used to effectively filter out the coherent emission of mid-infrared lasers from the co-propagating incoherent emission of a broadband thermal source. We show coherent light suppression as high as 16.9 dB without any modification of the broadband incoherent background spectrum. In addition, we demonstrate the ability to measure the spatially dependent (incoherent) thermal emission from a patterned surface, using our filter to remove a coherent signal which would otherwise overload our detection system. The demonstrated filter is rapidly tunable and wavelength-flexible, and has potential for imaging and spectroscopy applications in the presence of an otherwise overpowering coherent signal. 

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4. HQ-Filter: Hierarchy-Aware Filter For Empty-Resulting Queries in Interactive Exploration

   https://doi.org/10.1109/MDM52706.2021.00019  

   Sevim, Akil; Eldawy, Ahmed (June 2021, The IEEE International Conference on Mobile Data Management, MDM)

   null (Ed.)

   Modern visual data exploration systems are designed as client-server applications where the front-end interface generates a large number of queries to the back-end which are handled by a database server. As data exploration being a trial and error process, a significant amount of these queries return an empty result, which does not change the state of the visualization. These requests still add a significant overhead on network communication, request handling, and data processing. Moreover, given the virtually unlimited query space, it is impractical to enumerate and send all empty (or all non-empty) queries to the client to filter them. This paper introduces HQ-Filter, a hierarchy-aware filter for empty resulting queries, which utilizes the hierarchical nature of the data to construct a configurable and probabilistic filter. HQ-Filter can filter out empty-resulting queries at the client-side with a minimal size and processing overhead. HQ-Filter is applied to two existing data exploration systems for geospatial data, UCR-Star and Cloudberry. In both cases, it can successfully eliminate hundreds of queries per user which results in up-to 66% increase in server capacity by providing up to 15x speedup for average response time and up to 90% decrease in the server workload. 

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5. EPF: Evil Packet Filter

   Jin, Di; Atlidakis, Vaggelis; Kemerlis, Vasileios P. (July 2023, Proceedings of the USENIX Annual Technical Conference)

   The OS kernel is at the forefront of a system's security. Therefore, its own security is crucial for the correctness and integrity of user applications. With a plethora of bugs continuously discovered in OS kernel code, defenses and mitigations are essential for practical kernel security. One important defense strategy is to isolate user-controlled memory from kernel-accessible memory, in order to mitigate attacks like ret2usr and ret2dir. We present EPF (Evil Packet Filter): a new method for bypassing various (both deployed and proposed) kernel isolation techniques by abusing the BPF infrastructure of the Linux kernel: i.e., by leveraging BPF code, provided by unprivileged users/programs, as attack payloads. We demonstrate two different EPF instances, namely BPF-Reuse and BPF-ROP, which utilize malicious BPF payloads to mount privilege escalation attacks in both 32- and 64-bit x86 platforms. We also present the design, implementation, and evaluation of a set of defenses to enforce the isolation between BPF instructions and benign kernel data, and the integrity of BPF program execution, effectively providing protection against EPF-based attacks. Our implemented defenses show minimal overhead (<3%) in BPF-heavy tasks. 

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