On Regularly Branched Maps

Let $f\colon X\to Y$ be a perfect map between finite-dimensional metrizable spaces and $p\geq 1$. It is shown that the space $C^*(X,\R^p)$ of all bounded maps from $X$ into $\R^p$ with the source limitation topology contains a dense $G_{\delta}$-subset consisting of $f$-regularly branched maps. Here, a map $g\colon X\to\R^p$ is $f$-regularly branched if, for every $n\geq 1$, the dimension of the set $\{z\in Y\times\R^p: |(f\times g)^{-1}(z)|\geq n\}$ is $\leq n\cdot\big(\dim f+\dim Y\big)-(n-1)\cdot\big(p+\dim Y\big)$. This is a parametric version of the Hurewicz theorem on regularly branched maps.Comment: 12 page

On Finite-Dimensional Maps II

Let $f\colon X\to Y$ be a perfect $n$-dimensional surjection of paracompact spaces with $Y$ being a $C$-space. We prove that, for any $m\geq n+1$, almost all (in the sense of Baire category) maps $g$ from $X$ into the $m$-dimensional cube have the following property: $g(f^{-1}(y))$ is at most $n$-dimensional for every $y\in Y$.Comment: 8 page

On Throughput Maximization of Grant-Free Access with Reliability-Latency Constraints

Enabling autonomous driving and industrial automation with wireless networks poses many challenges, which are typically abstracted through reliability and latency requirements. One of the main contributors to latency in cellular networks is the reservation-based access, which involves lengthy and resource-inefficient signaling exchanges. An alternative is to use grant-free access, in which there is no resource reservation. A handful of recent works investigated how to fulfill reliability and latency requirements with different flavors of grant-free solutions. However, the resource efficiency, i.e., the throughput, has been only the secondary focus. In this work, we formulate the throughput of grant-free access under reliability-latency constraints, when the actual number of arrived users or only the arrival distribution are known. We investigate how these different levels of knowledge about the arrival process influence throughput performance of framed slotted ALOHA with $K$-multipacket reception, for the Poisson and Beta arrivals. We show that the throughput under reliability-latency requirements can be significantly improved for the higher expected load of the access network, if the actual number of arrived users is known. This insight motivates the use of techniques for the estimation of the number of arrived users, as this knowledge is not readily available in grant-free access. We also asses the impact of estimation error, showing that for high reliability-latency requirements the gains in throughput are still considerable.Comment: Accepted for publication in ICC'201

Deep exclusive charged π\pi electroproduction above the resonance region

A description of exclusive charged pion electroproduction $(e,e'\pi^{\pm})$ off nucleons at high energies is proposed. The model combines a Regge pole approach with residual effect of nucleon resonances. The exchanges of $\pi$(140), vector $\rho(770)$ and axial-vector $a_1(1260)$ and $b_1(1235)$ Regge trajectories are considered. The contribution of nucleon resonances is described using a dual connection between the exclusive hadronic form factors and inclusive deep inelastic structure functions. The model describes the measured longitudinal, transverse and interference cross sections at JLAB and DESY. The scaling behavior of the cross sections is in agreement with JLAB and deeply virtual HERMES data. The results for a polarized beam-spin azimuthal asymmetry in $(\vec{e},e'\pi^{\pm})$ are presented. Model predictions for JLAB at 12 GeV are given.Comment: 29 page

Spatial interaction modeling of interregional commodity flows

Understanding the determinants of interregional commodity flows is critical for both transportation infrastructure planning (highways, railroad tracks, river/port facilities) and regional development policies (location of activities, reducing regional disparities). Unfortunately, limited data availability has, in the past, hindered empirical research in this area. Drawing from both the spatial price equilibrium theoretical framework and the empirical literature on spatial interaction modeling and international trade, this paper expands past spatial interaction models of commodity flows by incorporating new variables into the model, using a flexible Box-Cox functional form, and applying the analysis to all manufacturing commodities. The recently released 1993 U.S. Commodity Flows Survey provides the empirical basis for estimating state-to-state flow models for 16 commodity groups over the 48 continental U.S. states. Based on input-output considerations and in order to differentiate intermediate from final commodity demands, the new variables include more detailed descriptions of the economies of the origin and destination states, such as employment and value added for the commodity sector at the origin state, wholesale employment at both ends, manufacturing employment at the destination state, and population and per-capita income at both ends. In addition, the average establishment size for the commodity at the origin is intended to measure scale or diversification effects. The competitive or agglomerative effects of the economic spatial structure are captured with competing destination and intervening opportunities variables. In addition to the average hauling distance between states, the model includes dummy variables measuring whether (1) having a common physical border, and (2) the origin or destination states being custom districts, have an effect on flows. Overall, the results show that the selected variables and functional form are very successful in explaining flow variations. The optimized Box-Cox specification proves to be superior to the log-log one in all cases. The results include the following findings: (1) the distance effect is negative and highly significant, with bulkier products hauled over shorter distances; (2) the adjacency effect is significant, with neighboring states trading more with one another, even after accounting for distance; (3) the impact of the spatial structure is of the competitive type in most cases; (4) the effects of imports and exports are significant for specific commodities; (5) wholesale activities at both origins and destinations are important facilitators of commodity flows; (6) except in one case (furniture), flows increase with product diversification; and (7) the role of intermediate and final demands for the commodities are clearly reflected by the selected employment, population and per-capita income variables. Various areas for further research are outlined.