Unbounded Capacity Research Articles

The unified process interaction worldview

ABSTRACT The process interaction worldview (PI) provides a description of a simulation model based on the life cycles of its entities. PI has traditionally been described under two perspectives: active resource and active transaction. While many simulation languages support the active transaction approach, the active resource has generally been adopted by M&S formalisms aimed to support modular models. In this paper we introduce the Unified Process Interaction Worldview (UPI) as a representation enabling the benefits of both active resource and active transaction perspectives. UPI is based on HyFlow, a formalism for representing hybrid systems using the process interaction worldview. To show UPI capabilities, we provide a simplified model of an oven with unbounded capacity. The solution of the ordinary differential equations (ODEs) describing oven and inside items temperatures, is computed by exponential time differentiating (ETD) integrators that are also represented in the HyFlow formalism.

Role of Ganetespib, an HSP90 Inhibitor, in Cancer Therapy: From Molecular Mechanisms to Clinical Practice.

Heat-shock proteins are upregulated in cancer and protect several client proteins from degradation. Therefore, they contribute to tumorigenesis and cancer metastasis by reducing apoptosis and enhancing cell survival and proliferation. These client proteins include the estrogen receptor (ER), epidermal growth factor receptor (EGFR), insulin-like growth factor-1 receptor (IGF-1R), human epidermal growth factor receptor 2 (HER-2), and cytokine receptors. The diminution of the degradation of these client proteins activates different signaling pathways, such as the PI3K/Akt/NF-κB, Raf/MEK/ERK, and JAK/STAT3 pathways. These pathways contribute to hallmarks of cancer, such as self-sufficiency in growth signaling, an insensitivity to anti-growth signals, the evasion of apoptosis, persistent angiogenesis, tissue invasion and metastasis, and an unbounded capacity for replication. However, the inhibition of HSP90 activity by ganetespib is believed to be a promising strategy in the treatment of cancer because of its low adverse effects compared to other HSP90 inhibitors. Ganetespib is a potential cancer therapy that has shown promise in preclinical tests against various cancers, including lung cancer, prostate cancer, and leukemia. It has also shown strong activity toward breast cancer, non-small cell lung cancer, gastric cancer, and acute myeloid leukemia. Ganetespib has been found to cause apoptosis and growth arrest in these cancer cells, and it is being tested in phase II clinical trials as a first-line therapy for metastatic breast cancer. In this review, we will highlight the mechanism of action of ganetespib and its role in treating cancer based on recent studies.

Transportation Problem Allowing Sending and Bringing Back

This paper considers a transportation problem on a weighted graph. The weights specify the amounts of commodities at nodes, which are positive if the amounts are stored at nodes and negative if the amounts are needed at nodes. To meet all demands we use vehicles, one at each node, with some loading capacity to and from neighbors. In a trip using a vehicle we can send commodities from a node to a neighbor along an edge and also bring back some other commodities from the neighbor. In this paper we are interested in feasibility problem, which is to decide whether there is a single round of trips that meet all demands. We prove the feasibility problem is NP-complete even in the easiest case of a one-commodity transportation problem with unbounded capacity. We also present several different polynomial-time algorithms for other cases.

Decentralized payment clearing using blockchain and optimal bidding

In this paper, we construct a decentralized clearing mechanism which endogenously and automatically provides a claims resolution procedure. This mechanism can be used to clear a network of obligations through blockchain. In particular, we investigate default contagion in a network of smart contracts cleared through blockchain. In so doing, we provide an algorithm which constructs the blockchain so as to guarantee the payments can be verified and the miners earn a fee. We, additionally, consider the special case in which the blocks have unbounded capacity to provide a simple equilibrium clearing condition for the terminal net worths; existence and uniqueness are proven for this system. Finally, we consider the optimal bidding strategies for each firm in the network so that all firms are utility maximizers with respect to their terminal wealths. We show that a pure strategy Nash equilibrium need not exist, and then look for mixed Nash equilibrium bidding strategies. The implications of these strategies, and more broadly blockchain, on systemic risk are considered.

Absorbing-state phase transition and activated random walks with unbounded capacities

In this article, we study the existence of an absorbing-state phase transition of an Abelian process that generalises the Activated Random Walk (ARW). Given a vertex transitive $G=(V,E)$, we associate to each site $x \in V$ a capacity $w_x \ge 0$, which describes how many inactive particles $x$ can hold, where $\{w_x\}_{x \in V}$ is a collection of i.i.d random variables. When $G$ is an amenable graph, we prove that if $\mathbb E[w_x] 0$. Moreover, in the former case, we provide bounds for the critical density that match the ones available in the classical Activated Random Walk.

Pilot Decontamination Processing in Cell-Free Massive MIMO

This letter focuses on the pilot contamination problem in the uplink and downlink of cell-free massive multiple-input multiple-output networks with different degrees of cooperation between access points. The optimum minimum mean square error processing can take advantage of large-scale fading coefficients for canceling the interference of pilot-sharing user-equipments and thus achieves asymptotically unbounded capacity. However, it is computationally demanding and can only be implemented in a fully centralized network. Here, sub-optimal schemes are derived that provide unbounded capacity with linear-growing complexity and using only local channel estimates but global channel statistics. This makes them suited for both centralized and distributed networks. In this latter case, the best performance is achieved with a generalized maximum ratio combiner that maximizes a capacity bound based on channel statistics only.

Multichannel Generations of Orbital Angular Momentum Modes with On‐Demand Characteristics on a Chip

AbstractThe orthogonality among optical beams with different orbital angular momentum (OAM) modes presents a new perspective as independent data‐carrying channels for multiplexing and demultiplexing. In particular, the theoretically infinite topological charge of OAM beam promises the unbounded capacity in communication systems. As a key part for the advancement of OAM technologies, OAM source has attracted considerable interest and experienced a rapid development. Nevertheless, conventional approaches to create OAM modes mainly rely on the use of bulky optical devices and external laser source, preventing their implementation into a miniaturized system. As a contrast, on‐chip generation of OAM beams with a built‐in source stands out with several advantages, including small footprint, compactness, portability, and high‐power efficiency. In this work, a versatile approach to directly produce OAM modes with on‐demand characteristics on a chip is demonstrated. Featuring the judicious combination of the emerging dielectric metasurface with the standard vertical cavity surface‐emitting laser (VCSEL) platform, the approach represents a feasible solution to the wide implementation of wafer‐level OAM emitters for optoelectronic integrations. Prototype laser chips for the generation of both individual OAM beam and OAM array with novel functionalites, such as controllable directionality and spatially varying topological charge and distribution, are systematically presented.

Cadence Clarity 3D Transient Solver

In this paper, we introduce the feature of Cadence Clarity 3D Transient Solver, a system-level simulation solution that solves electromagnetic interference (EMI) system design issues up to 10x faster than legacy 3D field solvers and offers unbounded capacity. Built on massively parallel solver technology, the Clarity 3D Transient Solver handles workload levels that previously required time-consuming and expensive anechoic test chambers to test prototypes for electromagnetic compatibility (EMC) compliance

Decentralized Payment Clearing using Blockchain and Optimal Bidding

In this paper, we construct a decentralized clearing mechanism which endogenously and automatically provides a claims resolution procedure. This mechanism can be used to clear a network of obligations through blockchain. In particular, we investigate default contagion in a network of smart contracts cleared through blockchain. In so doing, we provide an algorithm which constructs the blockchain so as to guarantee the payments can be verified and the miners earn a fee. We, additionally, consider the special case in which the blocks have unbounded capacity to provide a simple equilibrium clearing condition for the terminal net worths; existence and uniqueness are proven for this system. Finally, we consider the optimal bidding strategies for each firm in the network so that all firms are utility maximizers with respect to their terminal wealths. We first look for a mixed Nash equilibrium bidding strategies, and then also consider Pareto optimal bidding strategies. The implications of these strategies, and more broadly blockchain, on systemic risk are considered.

The Objects of Rational Thought (a Sketch)

Abstract Hilary Putnam’s wide ranging thought turned on an axis: an idea of the shape of an object of rational thought, a reflection of a rational being’s unbounded capacity for unprejudiced self-criticism. The idea unfolds in a particular way the motto “The conceptual cannot take care of itself.” No stock of concepts can derive their content merely from structural relations between them, no matter how complex. What more there is to content, on this unfolding, lies in a concept’s unbounded openness to world-dependence. This essay works through that idea in and through positioning Putnam in relation to two other great philosophers, Leibniz and Frege.

Bridging the gap between visual temporary memory and working memory: The role of stimuli distinctiveness.

Visual working memory (VWM) is traditionally assumed to be immune to proactive interference (PI). However, in a recent study (Endress & Potter, 2014), performance in a visual memory task was superior when all items were unique and hence interference from previous trials was impossible, compared to a standard condition in which a limited set of repeating items was used and stimuli from previous trials could interfere with the current trial. Furthermore, when all the items were unique, the estimated memory capacity far exceeded typical capacity estimates. Consequently, the researchers suggested the existence of a separate memory buffer, the "temporary memory," which has an unbounded capacity for meaningful items. However, before accepting this conclusion, methodological differences between the repeated-unique procedure and typical estimates of VWM should be considered. Here, we tested the extent to which the exceptional set of heterogeneous, complex, meaningful real-world objects contributed to the large PI in the repeated-unique procedure. Thus, the same paradigm was employed with a set of real-world objects and with homogenous sets (e.g., houses, faces) in which the items were meaningful, yet less visually distinct, and participants had to rely on subtle visual details to perform the task. The results revealed a large PI effect for real-world heterogeneous objects, but substantially smaller effects for the homogenous sets. These findings suggest that there is no need to postulate a new memory buffer. Instead, we suggest that VWM capacity and vulnerability to PI are highly influenced by task characteristics, and specifically, by the stimuli distinctiveness. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Max-pressure traffic controller based on travel times: An experimental analysis

The traffic control of an arbitrary network of signalized intersections is considered. This work presents a new version of the recently proposed max-pressure controller, also known as back-pressure. The most remarkable features of the max-pressure algorithm for traffic signal control are: scalability, stability, and distribution. The modified version presented in this paper improves the practical applicability of the max-pressure controller by considering as input travel times instead of queue lengths. The two main practical advantages of this new version are: (i) travel times are easier to estimate than queue lengths, and (ii) max-pressure controller based on travel times has an inherent capacity-aware property, i.e., it takes into account the finite capacity of each link. Travel time tends to diverge when the queue length is close to its capacity. It should be noted that previous max-pressure algorithms rely exclusively on queue length measurements, which may be difficult to accomplish in practice. Moreover, these previous algorithms generally assume queues with unbounded capacity. This may be problematic because a model with unbounded capacity links is not able to reproduce spillbacks, which are one of the most critical phenomena that a traffic signal controller should avoid. After presenting the new version of the max-pressure controller, it is analyzed and compared with existing control policies in a microscopic traffic simulator. Moreover, results of a real implementation of the developed algorithm to a signalized intersection, located at an urban arterial in Jerusalem, are shown and analyzed. To the best of the authors’ knowledge, this experiment is the first real implementation of a max-pressure controller at a signalized intersection.

Multi-Cell MMSE Combining Over Correlated Rician Channels in Massive MIMO Systems

This letter investigates the uplink of massive MIMO systems using multi-cell MMSE (M-MMSE) combining that was shown to yield unbounded capacity in Rayleigh fading. All intra and inter-cell channels are correlated with distinct per-user Rician factors and channel correlation matrices, pilot contamination and imperfect channel estimation. First, a closed-form approximation of the spectral efficiency (SE) is derived thus enabling to demonstrate that, under certain conditions on the correlation matrices, M-MMSE generates unbounded SE in Rician fading. Second, the impact of inter-cell LoS components is examined in favorable propagation conditions, and, interestingly, shown to be more beneficial in terms of SE than when these interfering links are entirely scattered.

Beyond 5G: The Role of THz Spectrum

There have been substantial technical and policy discussions about the spectrum needs of 5G and the necessity of expanding access to higher frequency spectrum, including in the millimeter wave (mmWave) bands from 30 to 300 GHz. The focus, however, has been on bands below 60GHz, or at most 90GHz, which is the current limit of near-future commercial technologies. As wireless markets continue to grow, demand may arise for spectrum in still higher frequency bands above 90GHz, including in the sub-millimeter or Terahertz (THz) bands between 300GHz and 3THz. Although exploiting THz bands is at the frontiers of technical research today and the commercial case for it will depend on further demonstration of the value and constraints, it is worthwhile exploring how THz spectrum might impact wireless network architectures, business/usage cases, and spectrum policy. In this paper, we explore those challenges. We first explain some of the critical features of THz spectrum that make it both attractive and challenging to use and summarize the current state of our ability to address those challenges by reference to the current engineering research and commercialization progress on exploiting mmWave and higher frequencies. For example, the THz spectrum would offer virtually unbounded capacity (relative to today's demand forecasts) for supporting wide-channels and extremely high data rates, but with demanding Line of Sight (LOS) requirements. THz devices operate in very narrow beams, close to optical wavelengths, and have very limited capability to penetrate materials (e.g., even a sheet of paper is sufficient to block it). Integrating such spectrum into wireless networks will impose important requirements for antenna siting (small cell architectures) and backhaul, posing greater challenges for extending core-network services to edge-networks. We hypothesize that such spectrum may further empower equipment-based, end-user deployed strategies for deploying wireless networking, with interesting implications for industry structure and regulatory policy. Furthermore, because current spectrum policies are limited to radio frequencies below 300GHz (arguably below 90GHz), THz is the green-field frontier for spectrum policy-making. This offers an opportunity for novel thinking about how best to manage spectrum resources to enable efficient sharing. Moreover, shifting wireless services to THz might free up capacity in the currently scarce lower frequency bands (below 10GHz), with implications for how we should think about spectrum management across all frequency bands. This includes addressing the challenge of the appropriate licensing regime (e.g., exclusive or unlicensed) that should apply for the THz spectrum. A better understanding of the potential uses for the terahertz spectrum is essential for a better understanding of scarcity limits on the lower frequency spectrum. Although the focus of the analysis will be on the THz spectrum, informed by recent technical work being directed by the authors, the applicability of the insights will be more general and applicable to today's efforts to promote spectrum policy reform, wireless network regulation, and realization of the future beyond 5G applications that we are striving to implement.

Comparison-Based Buffer Management in QoS Switches

The following online problem arises in network devices, e.g., switches, with quality of service (QoS) guarantees. In each time step, an arbitrary number of packets arrive at a single buffer and only one packet can be transmitted. The differentiated service concept is implemented by attributing each packet with a non-negative value corresponding to its service level. The goal is to maximize the total value of transmitted packets. We consider two models of this problem, the FIFO and the bounded-delay model. In the FIFO model, the buffer can store a limited number of packets and the sequence of transmitted packets has to be a subsequence of the arriving packets. In this model, a buffer management algorithm can reject arriving packets and preempt buffered packets. In the bounded-delay model, the buffer has unbounded capacity, but each packet has a deadline and packets can only be transmitted before their deadlines. Here, a buffer management algorithm determines the packet to be sent in each time step. We study comparison-based buffer management algorithms, i.e., algorithms that make their decisions based solely on the relative order between packet values with no regard to the actual values. This kind of algorithm proves to be robust in the realm of QoS switches. Kesselman et al. (SIAM J Comput 33(3):563–583, 2004) present two deterministic comparison-based online algorithms, one for each model, which are 2-competitive. For a long time, it has been an open problem, whether a comparison-based online algorithm exists, in either model, with a competitive ratio below 2. In the FIFO model, we present a lower bound of $$1+1/\sqrt{2} \approx 1.707$$ on the competitive ratio of any deterministic comparison-based algorithm and give an algorithm that matches this lower bound in the case of monotonic sequences, i.e., packets arrive in a non-decreasing order according to their values. In the bounded-delay model, we show that no deterministic comparison-based algorithm exists with a competitive ratio below 2. In the special s-uniform case, where the difference between the arrival time and deadline of any packet equals s, we present a randomized comparison-based algorithm that is 5 / 3-competitive.

Общий подход к решению задач на графах коллективом автоматов

We propose a general method to solve graph problems by a set of automata (computational agents) located in vertices of undirected ordered connected rooted graph and communicating by passing messages along graph edges. The automata are semi-robots, i.e., their internal memory size is sufficient to store values depending on the number of vertices and edges of the graph (n and m, correspondingly) but is too small to store the complete graph description. Section 2 presents classification of graph-based distributed computational models depending on internal memory size of vertex automaton, vertex automaton operation time, and edge capacity (the number of messages that are passing along an edge simultaneously). We choose for further use the model of maximum parallelism, having zero automaton operation time and unbounded edge capacity. It allows to obtain lower complexity bounds on distributed graph problems. Section 3 describes algorithm complexity assessment rules. Section 4 presents basic message processing procedures and message classification according to paths passed by them and methods of message processing by vertex automaton. We propose to construct algorithms solving graph problems on the base of the procedures considered, and present some examples in further sections. Sections 5-9 describe distributed algorithms for spanning tree construction, for task termination detection (based on detection of absence of messages used by the task), for shortest paths tree construction, for graph vertices enumeration, for collecting graph structure information in the root automaton memory (if it is unbounded). The algorithms proposed has linear time complexity in n and m, and use linear in n and m number of messages. Section 10 considers construction of maximum weight path in a weighted graph, which is the NP problem. We propose the algorithm that for the sake of using unbounded number of messages can solve this problem in linear time in n and m. The conclusion summarizes the paper and draws directions of further research: constructing algorithms for other graph problems and generalization of the approach to directed, non-deterministic and dynamic graphs.

An asymptotically optimal algorithm for large-scale mixed job shop scheduling to minimize the makespan

This paper considers the large-scale mixed job shop scheduling problem with general number of jobs on each route. The problem includes ordinary machines, batch machines (with bounded or unbounded capacity), parallel machines, and machines with breakdowns. The objective is to find a schedule to minimize the makespan. For the problem, we define a virtual problem and a corresponding virtual schedule, based on which our algorithm TVSA is proposed. The performance analysis of the algorithm shows the gap between the obtained solution and the optimal solution is O(1), which indicates the algorithm is asymptotically optimal.

On the complexity of the FIFO stack-up problem

We study the combinatorial FIFO stack-up problem. In delivery industry, bins have to be stacked-up from conveyor belts onto pallets with respect to customer orders. Given k sequences $$q_1, \ldots , q_k$$ of labeled bins and a positive integer p, the aim is to stack-up the bins by iteratively removing the first bin of one of the k sequences and put it onto an initially empty pallet of unbounded capacity located at one of p stack-up places. Bins with different pallet labels have to be placed on different pallets, bins with the same pallet label have to be placed on the same pallet. After all bins for a pallet have been removed from the given sequences, the corresponding stack-up place will be cleared and becomes available for a further pallet. The FIFO stack-up problem is to find a stack-up sequence such that all pallets can be build-up with the available p stack-up places. In this paper, we introduce two digraph models for the FIFO stack-up problem, namely the processing graph and the sequence graph. We show that there is a processing of some list of sequences with at most p stack-up places if and only if the sequence graph of this list has directed pathwidth at most $$p-1$$ . This connection implies that the FIFO stack-up problem is NP-complete in general, even if there are at most 6 bins for every pallet and that the problem can be solved in polynomial time, if the number p of stack-up places is assumed to be fixed. Further the processing graph allows us to show that the problem can be solved in polynomial time, if the number k of sequences is assumed to be fixed.

A Vision of a Future IoT Architecture Supporting Messaging, Storage, and Computation

In the future, things in the Internet of Things should be able to provide solutions for any task that we ask them to perform. Imagine that we would have hundreds of billions of devices connected to the Internet, each of these devices possibly has hundreds of gigabytes of storage and memory, a magnitude of giga instructions per second, and a bandwidth of gigabits per second. When these devices are connected in order to holistically work together, we would almost have an unbounded capacity. This paper introduces an architecture that utilizes all the available resources of the things on the Internet in hope to provide an unprecedented computational power to benefit society. There are three important features that a thing in this architecture could support: messaging, storage, and/or computation. With this architecture, a thing would be capable of discovering, working, and sharing with other things on the Internet. This architecture is based on the service-oriented concept to provide ease of use and implementation.

Robust Leader Election in a Fast-Changing World

We consider the problem of electing a leader among nodes in a highly dynamic network where the adversary has unbounded capacity to insert and remove nodes (including the leader) from the network and change connectivity at will. We present a randomized Las Vegas algorithm that (re)elects a leader in O(D\log n) rounds with high probability, where D is a bound on the dynamic diameter of the network and n is the maximum number of nodes in the network at any point in time. We assume a model of broadcast-based communication where a node can send only 1 message of O(\log n) bits per round and is not aware of the receivers in advance. Thus, our results also apply to mobile wireless ad-hoc networks, improving over the optimal (for deterministic algorithms) O(Dn) solution presented at FOMC 2011. We show that our algorithm is optimal by proving that any randomized Las Vegas algorithm takes at least omega(D\log n) rounds to elect a leader with high probability, which shows that our algorithm yields the best possible (up to constants) termination time.